lucid dreaming and consciousness: a theoretical...
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Lucid Dreaming and Consciousness:A Theoretical Investigation
Master Degree Project in Cognitive Neuroscience
One year Advanced level 30 ECTS
Spring term 2015
Nuno Alexandre Pinto
Supervisor: Paavo Pylkkänen
Examiner: Antti Revonsuo
Declaration of authorship
Thesis title: Lucid Dreaming and Consciousness: A Theoretical Investigation
Author name: Nuno Alexandre Pinto
The above noted work is submitted to the School of Bioscience at the University of Skövde, as a final Master project toward the degree of Master of Science (M.Sc.) in Cognitive Neuroscience. The project has been supervised by Paavo Pylkkänen.
I, Nuno Alexandre Pinto, hereby declare that:
1. The above noted work has not previously been accepted in substance for any degree andis not being concurrently submitted in candidature for any other degree.
2. The above noted work is the result of my own investigations, except where otherwise stated. Where corrections services have been used, the extent and nature of the corrections have been clearly marked.
Nuno Alexandre Pinto 2015-06-12
II
Acknowledgements
First and foremost, I would like to thank my beloved better half for all the patience and
insightful comments on the manuscript, and for her cleverness in pointing out ways to retrieve
most precious articles, which greatly benefited the analysis. But mostly, for bearing with me
and my utmost foul moods in the darkest moments of research and writing: thank you Rita!
Secondly, I would like to express my gratitude to my supervisor Paavo Pylkkänen for
the suggestions and insights provided, and also for his availability throughout the process.
Thirdly, I am also grateful for Oskar McGregor seminars, in which he shared his ideas
about thesis writing, and for the subtitle suggestion.
These acknowledgements would not be complete without my expression of gratitude to
all the persons who, in some way or another, contributed to the development of what I am today.
All the experiences, all the dialogues, all the books... All that is seen and yet to be seen.
“Neither outer sense impressions nor inner images produce consciousness; rather
one and the same consciousness illuminates the sense world in waking and the
dream world in sleep.” (Thompson, 2015a, p. 187)
III
Table of Contents
Abstract V
Introduction 1
Part I – Main concepts definition and lucid dreaming history 3
1. Main concepts definition ….................................................................................... 3
2. Lucid dreaming history …...................................................................................... 6
Part II – Human sleep and dreaming 9
1. Human sleep: NREM and REM …........................................................................ 9
2. Human dreaming: from non-lucid to lucid …....................................................... 15
3. Human dreams: delusional hallucinations or creative imaginations? …............... 30
Part III – The cognitive neuroscience of lucid dreaming 33
1. The use of lucid dreams in cognitive neuroscience research …............................. 33
2. Contemporary cognitive neuroscience research with lucid dreaming.................... 39
Part IV – Lucid dreaming and consciousness 61
1. Bridges between lucid dreaming and consciousness …......................................... 61
2. The protoconsciousness and primary-secondary consciousness hypotheses …..... 66
3. Can lucid dreaming unveil consciousness? …....................................................... 71
4. The continuity of meta-awareness in consciousness research …........................... 78
Concluding remarks and bridges for the future 82
References 85
Appendix A 109
Appendix B 110
IV
Running head: LUCID DREAMING AND CONSCIOUSNESS
Abstract
The purpose of this theoretical investigation is to provide a conceptual and theoretical analysis
of the lucid dreaming phenomenon and its contribution for consciousness research. After a brief
introductory overview, the most relevant concepts are defined and a sketch of lucid dreaming
historical evolution is given. Secondly, an analysis of the main characteristics pertaining human
sleep and dreaming is done, leading to the grasp of the differences between non-lucid and lucid
dreams. Thirdly, one enters into the cognitive neuroscience of lucid dreaming per se,
approaching the ways of using it in the experimental setting, and also what has been done
contemporaneously, with a presentation of the neuroscientifical research line relevant for this
investigation. Fourthly, the connections between lucid dreaming and consciousness are
examined, in what relates to main theories and the usefulness of this phenomenon in
consciousness research. Lastly, some concluding remarks are in order, laying out some bridges
for the future.
Keywords: Lucid dreaming, Consciousness, Lucidity, Meta-cognition, REM sleep, Dreaming
V
LUCID DREAMING AND CONSCIOUSNESS 1
Lucid dreaming is one phenomenon that has accompanied mankind since early times
and, as so many others, was neglected by the scientific and academic world, relegated to a
more mystical or paranormal approach, in the same way as many other phenomena related to
sleep and dreaming (LaBerge & Rheingold, 1991). In the late XIX and XX century, it suffered
from being a nuisance to Freudian psychoanalysis (Tranquillo, 2014), staying dormant to
science up until the work of LaBerge and colleagues (LaBerge, Nagel, Dement, & Zarcone,
1981), who came up with a way to physiologically identify the exact moment lucid dreaming
was happening inside the dreaming subject. From then on, research and experiments on the
subject exploded, somehow replicating what had happened after the discovery of rapid-eye-
movement (REM) sleep and its connection to dreaming in the 1950's (Thompson, 2015b).
Nowadays, cognitive neuroscience of dreaming proposes pre-frontal deactivations
observed in REM sleep as the cause of the cognitive limitations experienced in non-lucid
dreaming. It would seem that there are human brain regions that become selectively deactivated
when compared to the waking state, such as the dorso-lateral pre-frontal cortex (DLPFC) and
the precuneus, and other regions that become more activated, such as the limbic and paralimbic
systems (Hobson & Pace-Schott, 2002; Nir & Tononi, 2010; Schwartz & Maquet, 2002;
Spoormaker, Czisch, & Dresler, 2010). In lucid dreaming state, it has been suggested that the
previously deactivated DLPFC re-activates, allowing for the awareness of being in a dream.
Likewise, it has been proposed that lucid dreaming associates with pre-frontal activations
(Hobson, 2009a; Hobson, Pace-Schott, & Stickgold, 2000; Karim, 2010; Spoormaker et al.,
2010; Tononi, 2009; Voss, Holzmann, Tuin, & Hobson, 2009).
In Hobson's view (2009a), lucid dreaming suggests that consciousness can be split into
two parts: an actor, in the guise of the dreamer, and an observer, in the guise of the awake,
becoming, in the author's opinion, a very attractive phenomenon for scientific investigation in
the realm of consciousness studies. So attractive indeed, that it can be said the human mind may
LUCID DREAMING AND CONSCIOUSNESS 2
be capable of being in two states at one time, waking and dreaming. In turn, this should make
possible for the experimental scientist to measure the physiological correlates of lucid dreaming
in the laboratory (Hobson, 2009a). It is also suggested that, to study consciousness, one would
need to track changes in the brain and in the mind simultaneously (Brylowsky, 2010; Hobson,
2005).
In line with what has been previously mentioned, the aim of this thesis is to provide a
conceptual and theoretical analysis of cognitive neuroscience field of lucid dreaming, in what
concerns its direct relation with the field of consciousness studies. The rationale behind this
objective lies in the permanence of the lucid dreaming phenomenon throughout mankind's
recent history, allied with the surge in contemporary cognitive neuroscience lucid dreaming
research connected with a particular aspect of consciousness studies.
For this purpose, it is important firstly to discern the neurophysiological details of
human sleep and dreaming relevant for the aim of the thesis, especially in what ways non-lucid
dreams differ from lucid ones, in a phenomenologically and neurophysiologically way, and how
the path to lucidity is spanned. Part II of this thesis - “Human Sleep and Dreaming” - will
attempt to accomplish this objective. Afterwards, on Part III, an overview of the cognitive
neuroscience of lucid dreaming is provided, focusing first in general guidelines on working with
lucid dreams, and then proceeding to an in-depth analysis of the most relevant experiments
from contemporary research. The last section of the manuscript deals with the main connections
between lucid dreaming and consciousness, relating to the main theory and hypotheses
connecting both fields, at the present moment.
Notwithstanding, it is important however to previously define some main concepts
relevant to this investigation and to have a brief review of the history of lucid dreaming. This
will be done in the next section.
LUCID DREAMING AND CONSCIOUSNESS 3
Part I – Main concepts definition and lucid dreaming history
1. Main concepts definition
For a clear understanding of the nomenclature used throughout this theoretical
investigation, central concepts clarification is in order. To accomplish that, succinct definitions
in the form of citations will be given, followed by short analysis, except in the case of lucid
dreaming, which is defined in a somewhat extended manner.
First of all, one can start by trying to clarify the concept of consciousness relevant for
this manuscript purposes, with the help of the Stanford Encyclopedia of Philosophy, and its
entry on the subject:
”The words “conscious” and “consciousness” are umbrella terms that cover a
wide variety of mental phenomena. Both are used with a diversity of meanings,
and the adjective “conscious” is heterogeneous in its range, being applied both to
whole organisms—creature consciousness—and to particular mental states and
processes—state consciousness” (Van Gulick, 2014, section 2).
Consciousness seems to be an umbrella term indeed, but for the purposes of this theoretical
investigation, it will be used as state consciousness, so as it seems to be used in contemporary
lucid dreaming research. Nevertheless, one can also refer to consciousness as “the subjective
psychological reality that we experience” (Revonsuo, 2010, p. 295), which may lead to
understanding it as the subjective experience of “I”, as in inner presence. These two definitions
seem to complement each other, as state consciousness may be the subjective reality that is
experienced as the brain moves back and forth through a continuum of states amid the sleep-
wake cycle, and many other so-called normal and altered states of consciousness, during the
temporal frame of a human life. This concept will be mentioned and discussed throughout the
document.
LUCID DREAMING AND CONSCIOUSNESS 4
Under the umbrella term of consciousness, one can also find the concepts of
phenomenal consciousness and reflective consciousness. Simply put, phenomenal
consciousness “is the current presence of subjective experiences, or the having of subjective
experiences. An organism possesses phenomenal consciousness if there is any type of
subjective experience currently present for it” (Revonsuo, 2006, p. 37). The notion of
phenomenal consciousness is said to be the most essential concept for the science of
consciousness, as it indicates the immediate presence of qualitative experience for a subject
(Revonsuo, 2006). One step further, there is a higher-order form of consciousness, or reflective
consciousness, which “involves a cognitive operation that adds something to and is separable
from the phenomenal content itself” (Revonsuo, 2006, p. 41). These two concepts are of a
fundamental nature as to discern the core of this theoretical investigation. It is through these
conceptualizations that lucid dreaming research is contemporaneously connected to
consciousness research, as it will be made progressively clear throughout the manuscript,
culminating in Part IV: “Lucid Dreaming and Consciousness”.
Secondly, the concept of dreaming may be succinctly defined as “complex, multimodal,
dynamic and progressive conscious experiences during sleep that are organized in the form of a
sensory-perceptual world or a world simulation” (Revonsuo, 2010, p. 295). This concept will be
discussed in more detail throughout the whole Part II: “Human Sleep and Dreaming”.
Inside dreaming, one finds the phenomenon of lucid dreaming, which can be shortly
defined as “a dream during which the dreamer recognizes that the ongoing experience is a
dream” (Revonsuo, 2010, p. 298). Taking this into account, one can also say that lucid dreams
are dreams in which the dreamer knows he is asleep (Brown, 1934), that is, dreams in which the
dreamer is in a state of consciousness similar in many ways to waking consciousness, but in
which the subject knows that he is still dreaming (LaBerge et al., 1981). Lucid dreamers report
being in possession of all their cognitive faculties, namely: to reason clearly, to remember
LUCID DREAMING AND CONSCIOUSNESS 5
conditions of waking life, and to act within the dream upon reflection or according to a plan
decided before going to sleep (Holzinger, LaBerge, & Levitan, 2006). Lucid dreaming seems to
be the stalwart awareness that one is dreaming and that is not really awake. By this standard, it
may even be possible to consider lucid dreaming paradoxical, as it seems to contain elements
from both waking and dreaming states consciousness (Hobson, 2009a).
In day-to-day lives one does not think about being awake while one is, and in a similar
manner, one is not aware that one is dreaming while it is (LaBerge & Gackenbach, 2000). This
seems to be contrastive with lucid dreaming, in which one knows that is experiencing a dream.
This awareness of dreaming seems to correlate with clarity of memory and reasoning, that
permits the dreamer to recall his waking life and control his own activities (Barrett, 1992; Van
Eeden, 1913).
Moreover, the concept of lucidity in lucid dreams seems to be based upon a progression
toward a completeness of waking abilities, that co-exists with the continuity of the dreaming
mode of experience, and this co-existing and interaction of the two modes constitutes the
lucidity in lucid dreaming (Barrett, 1992). In short, in what relates lucid dreaming, the defining
feature of lucidity is the cognitive realization of the fact that this is a dream (Revonsuo, 2010).
In addition, some authors point out that if when one dreams one is explicitly aware that
is dreaming, then lucid may also take a psychiatric sense, as a condition of clear insight and
correct orientation to reality. There seems to be a clear possession of one's cognitive abilities
while in lucid dreaming, and also a balance of detachment and participation, in which the actor
and observer perspectives may be present simultaneously (LaBerge & Gackenbach, 2000).
When studying dreams, their degree of lucidity, and its relation to consciousness, it is
also important to define the concept of awareness. Curiously enough, the word awareness in the
English language is a synonym for the word consciousness, and is defined as ”the quality or
state of being aware, consciousness” (Awareness, n.d.). For the purposes of this investigation,
LUCID DREAMING AND CONSCIOUSNESS 6
one can distinguish at least three types of awareness:
1. Awareness - as the phenomenal experiences of objects and events (Cicogna & Bosinelli;
2001)
2. Awareness - as self-awareness, the awareness of being one-self (Cicogna & Bosinelli;
2001)
3. Awareness - as meta-awareness, the awareness of mental life itself (Cicogna &
Bosinelli; 2001); or the ability to take explicit note of the current contents of
consciousness (Schooler, Smallwood, Christoff, Handy, Reichle, & Sayette, 2011)
These three types of awareness are important to apprehend, so as to grasp the influence of the
brain on the ability to be aware while it moves through various states. These concepts are also
being used throughout the manuscript.
One last concept to be construed is meta-cognition, or the ability to reflect on and report
one's own mental states (Filevich, Dresler, Brick, & Kühn, 2015). Other coadjuvant concepts
will appear in the text and will be defined on a first appearance basis. All previously mentioned
definitions are of paramount importance, not only for a clear understanding of such subjective
phenomena as the ones covered in this essay, but also as a guidance, taking into account that the
relevant literature is using many concepts without a clear common ground or agreement onto
exact meanings.
After this clarification, the next sub-section will draw a historical sketch of the way
lucid dreams have accompanied mankind literature and reasoning.
2. Lucid dreaming history
Aristotle (350 B.C.E.) was the first to note that sometimes we know that we are
dreaming while we dream, as he wrote on his treatise “On Dreams” that when one is asleep,
there is something in consciousness declaring that what presents itself is but a dream. From the
LUCID DREAMING AND CONSCIOUSNESS 7
eighth century onwards, lucid dreaming was cultivated in Tibetan Buddhism, and also known in
Sufism and Indian Yoga (Holzinger, 2009; Holzinger et al., 2006). The dream yogis of Tibet
used lucid dreams as an opportunity to experiment and realize the subjective nature of the
dream state and, as an extension, the waking experience (Holzinger, 2009). It was practised as a
form of yoga - Dream Yoga - and used to exercise the maintenance of consciousness during all
sleep stages. The final objective of the practice was to be able to maintain consciousness during
death so that the practitioner could consciously find the path to the other world (Holzinger et al.,
2006).
The first oneirologist, or pioneer of dream research, to systematically investigate and
collect dream reports on lucid dreaming, is considered to be Léon d'Hervey de Saint-Denys, a
Parisian French academic and professor of Chinese literature and language, that in 1867
anonymously published his 20 years of experience in dream research (Holzinger, 2009;
Holzinger et al., 2006). The term Lucid Dream was created by Frederik Willems van Eeden, a
Dutch psychiatrist, for a lecture given on the 22nd of April of 1913, at a meeting of the Society
for Psychical Research (SPR) in London, in which he spoke about how he had recorded three
hundred and fifty-two lucid dreams (Holzinger, 2009; Holzinger et al., 2006; Van Eeden, 1913).
More than half a century later, Paul Tholey (1991) named this experience Klartraum, or dreams
of clarity, and defined them as those dreams where the dreamer has complete consciousness and
awareness about the fact that he is dreaming, being able to interfere, influence, or even control
or create the dream (Holzinger, 2009; Holzinger et al., 2006).
It is exactly the more than two thousand years of lucid dream phenomena that provide
the rationale for expanding this area of human experience through neuroscience
experimentation (Brylowski, 2010). In that sense, although a challenging phenomenon to study,
lucid dreaming is a methodological paradigm that offers the potential for a deep understanding
of the brain basis of consciousness, and is becoming more and more a part of the mainstream
LUCID DREAMING AND CONSCIOUSNESS 8
cognitive neuroscience (Gackenbach, 2010; Gavie & Revonsuo, 2010; Mota-Rolim & Araujo,
2013).
In the next section, human sleep and dreaming are analysed in some detail, in what
concerns the neurophysiological and phenomenological aspects pertinent to this investigation.
LUCID DREAMING AND CONSCIOUSNESS 9
Part II – Human sleep and dreaming
One of the universal and sturdy changes in consciousness, that humans can observe in
themselves and in others, is the moment of loss of self-awareness induced by the transition from
waking to sleep. Even when some kind of awareness returns in sleep during dreaming, this self-
awareness is somehow different from wake state consciousness. One easy and simple way to
experience it is when awaking from a dream, as one perceives the velocity of the switch from
the self-awareness of dream state, to the self-awareness of waking state (Muzur, Pace-Schott, &
Hobson, 2002). Notwithstanding, in phenomenological terms, one of the most astonishing
features of conscious experiences in sleep may well be the similarity of the inner world of
dreams to the real world of wakefulness (Nir & Tononi, 2010).
1. Human sleep: NREM and REM
During sleep, the human brain repeatedly cycles through five main stages. The first four
of these sleep stages are conventionally called Non-Rapid-Eye-Movement, or NREM sleep, and
the fifth stage is known as Rapid-Eye-Movement, or REM sleep (Thompson, 2015b). NREM
and REM sleep are clearly distinguishable, and by convention are defined through the
electrophysiological signals detected by means of a combination of three techniques:
electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG)
(Muzur et al., 2002). These techniques taken together are usually called polysomnography
(PSG), even though the term PSG can accommodate other techniques as well. The EEG
technique basically records electrical activity at the scalp, that in turn can be used to identify
each sleep stage associating it to a distinct brain wave pattern. The EOG technique measures the
corneo-retinal standing potential found between the front and the back of the human eye, which
can be used to identify eye-movement direction. The EMG technique essentially records the
LUCID DREAMING AND CONSCIOUSNESS 10
electrical activity produced by skeletal muscles, in order to monitor and understand what kind
of muscular activity goes on, if any (Muzur et al., 2002; Thompson, 2015b).
NREM corresponds to an increasing depth of sleep, and is indicated by high-voltage and
low-frequency wave activity that progressively dominate the EEG register. Low frequency
waves prevail in stages three and four, which are the deepest, and are also called slow wave
sleep, delta sleep, or deep sleep. As the sleeping brain moves out of deep sleep, the large, slow
waves begin to change, more and more resembling the waves typical of the waking brain
(Thompson, 2015b). Likewise, this wake-like state has been called paradoxical sleep (Kahn &
Gover, 2010). In consequence, REM sleep corresponds to high or fast frequency and low
amplitude activity in the EEG, singlets and clusters of rapid eye movements in the EOG
channel, and very low levels of muscle tone, or muscle atonia, in the EMG channel. It also
correlates with a selective reactivation and deactivation of neural activity (Kahn & Gover, 2010;
Muzur et al., 2002).
To summarize, one can look at the characteristics of the physiological sleep stages
according to PSG, in a structured manner (Muzur et al., 2002; Thompson, 2015a):
NREM stage I (N1) – Eyes closed, slow eye-rolling movements, EEG alpha waves (8-
12 Hz) dwindle, slower theta waves (4-8 Hz) appear.
NREM stage II (N2) – Eye movements cease, 12-14 Hz bursts (sleep spindles) and brief
high voltage waves (K-complexes) occur.
NREM stage III (N3) – There is a blend of sleep spindles and high-amplitude, slow
frequency delta waves (0,5-4 Hz).
NREM stage IV (N4) – Almost exclusively delta waves (<4 Hz).
REM – High-frequency, low-amplitude waves, limb muscles paralysed, i.e. muscle
atonia, eyes closed with rapid eye movement.
LUCID DREAMING AND CONSCIOUSNESS 11
The evidence that the brain is highly active during sleep was first obtained with the
discovery of REM sleep and its correlation with dreaming. In 1953, Aserinsky and Kleitman
discovered that the eye movements, EEG pattern, and autonomic nervous system activity going
on in sleep were significantly correlated and did not occurred randomly, suggesting that these
physiological phenomena and dreaming were manifestations of a particular level of cortical
activity normally occurring during human sleep. Later on, in 1957, Dement and Kleitman
correlated eye movements during sleep with dream activity, creating an objective method for
the study of dreaming (Aserinsky & Kleitman, 1953; Dement & Kleitman, 1957).
During REM sleep, activation seems to be triggered in pontine regions while sensory
input is gated and motor output is suppressed, and for that reason the brain in REM sleep seems
to function as a closed loop system (Hobson & Pace-Shott, 2002). The noticing of this
simultaneous block of sensory inputs and motor outputs, sometimes called input-output gating
(Hobson & Pace-Shott, 2002), was also important, taking into account that this activation in
REM sleep is suggested to occur at regular ninty-minute intervals and is thought to occupy 20%
of sleep (Hobson, 2005; Kahn & Gover, 2010). Moreover, the development of magnetic
resonance-compatible EEG recording systems granted researchers the proficiency to obtain
PSG in strong magnetic fields, and to obtain functional magnetic resonance imaging (fMRI)
data during verified, unambiguous sleep, allowing non-invasive measurements of neural activity
changes with high spatial resolution (Dresler, Spoormaker, Wehrle, & Czisch, 2014b).
NREM sleep appears to be outlined by widespread deactivations in the human brain,
compared to wakefulness, as seen with fMRI-measured cerebral activity (Kaufmann et al.,
2006). However, on the background of these deactivations, specific regional activity can be also
observed with the use of fMRI, such as neural correlates of sleep EEG micro-processes: slow-
waves (Dang-Vu et al., 2008), K-complexes (Caporro et al., 2012; Czisch et al., 2009; Jahnke et
al., 2012), and sleep spindles (Andrade et al., 2011; Caporro et al., 2012; Schabus et al., 2007).
LUCID DREAMING AND CONSCIOUSNESS 12
For instance, Andrade and colleagues (2011) have showed that fast sleep spindles appear
to be accompanied by increased neural activity in the thalamus, cingulate and pre-frontal
cortices, and pre- and post-central gyrus (Andrade et al., 2011). Moreover, processing of
external acoustic stimuli is pointed out to be suppressed during spindle activity (Schabus et al.,
2012), whereas the functional coupling between the hippocampus and the neocortex increases
(Andrade et al., 2011), leading to the idea of a spindle specific brain state, which may allow for
an information transfer increase between brain regions associated with memory processes
(Dresler et al., 2014b).
On the other hand, REM sleep is suggested to correlate with increased cerebral blood
flow in the thalamus, visual areas, and limbic regions (Braun et al., 1998; Maquet et al., 1996).
There seems to be reactivation of the limbic, para-limbic, and amygdala regions, thought to
associate with emotions, and also reactivation of the medial pre-frontal cortex (MPFC), implied
to associate with internally motivated behaviour (Braun et al., 1998; Maquet et al., 1996). At the
same time, the precuneus, thought to correlate with with body location, and the DLPFC,
proposed to associate with executive functions, autobiographical memory recall, and goal
selection, appear to be selectively deactivated (Braun et al., 1998; Kahn & Gover, 2010; Maquet
et al., 1996).
REM sleep has recently been divided in two distinct components: phasic REM, in which
one can find periods of eye movement activity and high cortical activation, and tonic REM, in
which one can find periods with few eye movements and relatively low activation (Dresler et
al., 2014b; LaBerge & Gackenbach, 2000). Indeed, there appear to be differences in sensory
processing and in thalamocortical activity patterns during phasic and tonic REM sleep periods
in humans (Wehrle et al., 2007). There seems to be no reaction to sensory stimuli in periods
containing bursts of phasic REM activity, whereas acoustic stimulations elicit residual
activations of the auditory cortex during tonic REM sleep (Wehrle et al., 2007). This may
LUCID DREAMING AND CONSCIOUSNESS 13
demonstrate a strong decrease in brain reactivity to acoustic stimulation during phasic REM
sleep periods, while the processing to the stimulus is maintained, to some extent, during tonic
REM sleep, when compared to waking state (Dresler et al., 2014b; LaBerge & Gackenbach,
2000; Wehrle et al., 2007).
All in all, there seems to be residual external stimulus processing during tonic REM
periods, whereas in phasic REM sleep the brain apparently functions in a closed loop (Wehrle et
al., 2007). This neural divide may help explain why sometimes external stimuli are incorporated
into the dream narrative, while other times the same stimuli are ignored or lead to awakening
(Dresler et al., 2014b; Wehrle et al., 2007). Likewise, it has been proposed that prototypical
dreaming is bound to phasic REM sleep, whereas tonic REM sleep seems to be associated with
dreaming activity similar to that of NREM sleep, in a qualitative way (Dresler et al., 2014b;
LaBerge & Gackenbach, 2000; Wehrle et al., 2007).
Moreover, through the study of human sleep disorders one can ascertain that sleep may
be a local brain phenomenon, instead of a global one, and that wakefulness, REM, and NREM
sleep may not be mutually exclusive states. This is to say that different brain regions may be in
different states at the same time (Nir & Tononi, 2010). As an illustration, this can be observed in
a NREM parasomnia – sleepwalking - where thalamocingulate pathways are as active as in
waking state, while the rest of the cerebral cortex is in NREM sleep (Mahowald & Schenk,
2005). It can also be noticed in a REM parasomnia - REM sleep behaviour disorder (RBD) -
where somatic muscle atonia, one of the defining features of REM sleep, is absent, allowing for
dream mentation acting out, often with violent or injurious results (Mahowald & Schenk, 2005).
In a more general way, Hobson (2009b) suggests sleep as a recovery process in
homoeothermic animals, like humans, which seem to require it to maintain body weight and
body temperature (Siegel, 2005). In fact, only mammals and birds are thought to be
homoeothermic, and are also pointed as the only animals to display REM sleep (Hobson,
LUCID DREAMING AND CONSCIOUSNESS 14
2009b; Parmeggiani, 2003). Furthermore, the concept that humans appear to only cognize
effectively in a narrow range of brain temperature, may suggest that consciousness probably
depends on homoeothermy and, in turn, homoeothermy may depend on sleep (Hobson, 2009b).
Sleep deprivation is said to cause psychological dysfunction, which seems to support the idea
that the integrity of waking state consciousness depends on the integrity of dream state
consciousness, and that on the brain mechanisms of REM sleep (Hobson, 2009b; Muzur et al.,
2002).
In summary, and according to what has been mentioned and discussed in this sub-
section, sleep seems to be an active brain process, and represents two somehow different states
of being, NREM and REM sleep (Nir & Tononi, 2010). These states are neurophysiologically
different from each other as each is from wakefulness, and it would seem that most parts of the
brain are active during all these three states of being, in a different form (Hobson, 2005). A
reorganization of brain activity and function seems to be going on during these three states, and
research guided by human sleep disorders led to important basic sleep concepts (Mahowald &
Schenk, 2005). These concepts include the idea that sleep presents itself as local brain
phenomenon, instead of a global one, and state dissociation or inter-mixture seem to point out
that these three states are not mutually exclusive, but rather a continuum (Hobson, 2005; Nir &
Tononi, 2010; Rees, Kreiman, & Koch, 2002).
Moreover, and also mentioned before, sleep is pointed out to be an actively regulated
process and could be regarded as a reorganization of neuronal activity (Hobson, 2005; Nir &
Tononi, 2010). It appears to vary between species and during lifespan, suggesting its many
functions. Sleep, as we know it in larger mammals, is thought to correlate with relatively large
brains and with homoeothermy (Hobson, 2005; Hobson 2009b). The study of mental
experiences during sleep offers a unique opportunity to clarify how changes in brain activity
relate to changes in consciousness, because if it was not for sleep, it would be difficult to see
LUCID DREAMING AND CONSCIOUSNESS 15
that consciousness as a state depends on the way the brain is functioning (Hobson, 2005;
Mahowald & Schenk, 2005; Nir & Tononi, 2010; Rees et al., 2002). It would seem that ”sleep
and dreaming are a treasury of altered states of consciousness.” (Revonsuo, 2010, p. 251)
2. Human dreaming: from non-lucid to lucid
In Revonsuo's (2006) view, the dreaming brain is an exemplary system for the study of
consciousness, as it brings about all the sphere of subjective experience in a form that mirrors
waking reality. As such, for the science of consciousness, the dreaming brain may be a unique
model system (Revonsuo, 2006). Expanding on the definition given in Part I, sub-section 1,
dreaming can be further defined as ”a universal human mental state characterized by
hallucinatory imagery congruent with a confabulatory, temporally ordered, story-like
experience” (Pace-Schott, 2005, p. 563). In contrast, a more recent approach states dreaming
“exclusively in terms of consciousness and conscious experiences going on during sleep. More
particularly, dreaming is defined as subjective experience during sleep that simulates awake
experiences realistically” (Revonsuo, 2015, p. 57). This totally imaginary experience seems to
be accepted by the dreamer in the same way as waking percepts and events are.
According to Pace-Schott (2005), the importance of dreaming for neuroscience places
itself mainly in two pillars:
1. The single-mindedness and isolation of dreaming (Rechtschaffen, 1978), made evident
when the dreamer is absorbed in the dream world and plot, without any awareness of the
wake state alternative reality, except in lucid dreaming (Pace-Schott, 2005).
2. The fact that in dreams there are images, plots, characters, motor skills (flying),
emotions and memories that are created anew, without any connection with the
memories, abilities, characters or day-to-day tasks from the waking state (Pace-Schott,
2005).
LUCID DREAMING AND CONSCIOUSNESS 16
The functional neuroanatomy of human REM sleep and dreaming was mapped by
Maquet and colleagues in 1996, using positron emission tomography (PET) and PSG. The
regional cerebral blood flow (rCBF) distribution was recorded as an index of neuronal activity,
and all subjects recalled a dream after awakening from REM sleep. REM sleep associated with
intense neuronal activity, ocular saccades, muscular atonia and dreaming (Maquet et al., 1996).
The study results seemed to point out that the rCBF correlated positively with REM
sleep in the following brain locations: pontine tegmentum, left thalamus, both amygdaloid
complexes, anterior cingulate cortex, and right parietal operculum. The rCBF correlated
negatively with REM sleep in a vast area of the DLPFC, the parietal cortex, the posterior
cingulate cortex, and the precuneus. According to the authors, these results provided the first
comprehensive description of the distribution of cerebral activity during REM sleep in humans
(Maquet et al., 1996).
According to Muzur and colleagues (2002), unveiling the physiological basis of REM
sleep is to grasp that the ascending reticular activating system of the brainstem, as described in
waking state (Moruzzi & Magoun, 1949), is re-engaged during REM sleep, and the neuronal
basis of REM activation is to be found in the reciprocal interaction of aminergic and cholinergic
neurons in the pontine brainstem (McCarley & Hobson, 1975; Muzur et al., 2002).
In waking state, all main neuromodulatory brainstem systems seem to be available and
highly involved in goal-directed behaviour, such as: serotonin, norepinephrine, dopamine, and
acetylcholine (Kahn & Gover, 2010; Muzur et al., 2002). In REM sleep, two of these systems
apparently shut off: the locus coeruleus neurons, which modulate norepinephrine, and the dorso
raphe nucleus neurons, which modulate serotonin (Kahn & Gover, 2010; Muzur et al., 2002).
This change in brain chemistry, where the aminergic system shuts down while the
cholinergic system remains high, seems to be behind the occurrence of the so-called
hallucinatory images, the reduced ability to recognize the implausibility of the dream scenario,
LUCID DREAMING AND CONSCIOUSNESS 17
and the reduced ability to stay focused, typical of the non-lucid REM dream which, in a sense,
seems to have a mind of its own (Kahn & Gover, 2010).
Notwithstanding, dreaming may not be exclusively happening in REM sleep, since
NREM sleep awakenings yield reports of mental activity from stages N1, N2, and N3 (Foulkes,
1962; Nielsen, 2000). It is estimated, from an extensive review done by Nielsen (2000), a
general recall rate frequency of 42,5% from NREM sleep awakenings, so-called mental
experiences or sleep mentations. This figure clearly contrasts with the 81,8% recall rate
frequency from REM sleep awakenings (Nielsen, 2000; Pace-Schott, 2005). It is also suggested
that brain activation processes occurring outside PSG recorded REM, so-called covert REM,
may be in the origin of NREM dreaming (Nielsen, 2000; Pace-Schott, 2005).
Nevertheless, this general estimation hides in itself great variations, as a zoom-in
analysis can detail. For instance, reports from NREM N1 are frequent, between 80% to 90% of
the time, but short (Nielsen, 2000). In this sleep stage, vivid hallucinatory experiences are
reported, commonly defined as hypnagogic hallucinations, which are often static, similar to
single snapshots (Hobson & Pace-Schott, 2002; Hobson et al., 2000) that frequently do not
include a self character (Foulkes, 1985). On the other hand, awakenings from NREM N2 and
N3 yield reports of some experienced content in 50% to 70% of the occasions (Nielsen, 2000),
even though it may vary during the night and between subjects (Nir & Tononi, 2010). In
moments when NREM N3 is prevalent, and many large slow waves dominate the EEG,
awakenings appear to return few reports (Stickgold, Malia, Fosse, Propper, & Hobson, 2001).
Regularly, NREM awakening reports are qualitatively different from typical REM sleep
ones, meaning that they are usually short, thought-like, less vivid, less visual and more
conceptual, less motorically animated, under greater volitional control, more plausible, more
concerned with current issues, less emotional and less pleasant (Fosse, Stickgold, & Hobson,
2001; Hobson et al., 2000). The average length of REM sleep reports seems to increase with the
LUCID DREAMING AND CONSCIOUSNESS 18
duration of the REM sleep episode, contrary to what happens in NREM sleep (Hobson et al.,
2000).
Moreover, REM dream reports are more frequent, longer, more bizarre, more visual,
more motorically animated, and more emotional than NREM dream reports (Hobson et al.,
2000; Pace-Schott, 2005). It would seem that REM sleep exhibits much more gamma frequency
fast brain waves or rhythms, from 30 Hz to 80 Hz, than NREM sleep (Pace-Schott, 2005), as
measured by EEG (Corsi-Cabrera, Guevara, & Del Río-Portilla, 2008; Corsi-Cabrera, Miro, Del
Río-Portilla, Pérez-Garci, Villanueva, & Guevara, 2003), intracranial EEG (iEEG) (Gross &
Gotman, 1999; Nishida et al., 2005), and magnetoencephalography (MEG) (Corsi-Cabrera et
al., 2008). When in waking state, these oscillations are thought to be associated with attention to
stimuli and active cognition (Jensen, Kaiser, & Lachaux, 2007; Pace-Schott, 2005).
In contrast, NREM sleep, notably N3 and N4, reveals little gamma activity, correlating
instead with slow brain waves produced by recurrent interactions between the thalamus and
cortex (Pace-Schott, 2005). These recurrent interactions produce slower oscillations, as in sleep
spindles and delta waves, which can also be called corticothalamocortical rhythms, and in turn
associate with the cortical slow (<1 Hz) oscillation that groups in time the other
corticothalamocortical oscillations (Achermann & Borbely, 1997; Pace-Schott, 2005; Steriade,
2000). This slow oscillation seems to consist of periods of neuronal quiescence, alternating with
shorter periods of rapid neuronal firing (Destexhe, Hughes, Rudolph, & Crunelli, 2007; Pace-
Schott, 2005). This may be the cause of dreams lower frequency in NREM sleep (Hobson et al.,
2000; Pace-Schott, 2005).
Studies with EEG and MEG suggest that phasic REM sleep is accompanied by brain
activity that may be related to dream phenomena (Pace-Schott, 2005), such as: visual imagery
(Conduit, Crewther, & Coleman, 2004; Ogawa, Nittono, & Hori, 2005), enhanced cognitive
activity and attention (Corsi-Cabrera et al., 2008; Jouny, Chapotot, & Merica, 2000; Nishida et
LUCID DREAMING AND CONSCIOUSNESS 19
al., 2005), decoupling of executive control and perception (Cantero, Atienza, Madsen, &
Stickgold, 2004; Corsi-Cabrera et al., 2003, 2008; Perez-Garci, Del Río-Portilla, Guevara, Arce,
& Corsi-Cabrera, 2001), and enhanced emotional processing (Abe, Ogawa, Nittono, & Hori,
2008; Corsi-Cabrera et al., 2008; Ioannides et al., 2004).
REM sleep deprivation or circadian manipulations appear to intensify the occurrence of
dreams in NREM sleep (Nir & Tononi, 2010; Pace-Schott, 2005). REM sleep dreaming seems
to be more related to imagination than to perception, as it is known from lesion studies that
dreaming requires an intact temporo-parieto-occipital junction, and that lesions in this area also
affect mental imagery in wakefulness (Nir & Tononi, 2010; Pace-Schott, 2005).
Picking up the distinctions put forward by Nir and Tononi (2010), one could say that
dream consciousness is fascinating, if one looks into the ways it neurophysiologically differs
from waking consciousness:
1. Reduced voluntary control and volition - In dreaming there seems to be a prominent
reduction of voluntary control of action and thought. The right inferior parietal cortex
(Brodmann's area 40) appears to be deactivated during REM sleep, and this may help to
explain this reduction, since this area seems to have a role in waking volition (Braun et
al., 1997; Desmurget, Reilly, Richard, Szathmari, Mottolese, & Sirigu, 2009; Goldberg,
Ullman, & Malach, 2008; Maquet et al., 1996).
2. Reduced self-awareness and altered reflective thought - Holding contradictory beliefs is
a common feature, as is accepting strange or non-replicable events in wake
consciousness, such as flying (Hobson, Stickgold, & Pace-Schott, 1998). This may be
connected to the deactivation of certain brain regions, such as: the posterior cingulate
cortex, the inferior parietal cortex, the orbito-frontal cortex, and the DLPFC (Braun et
al., 1997; Maquet et al., 1996).
3. High degree of emotionality or emotional involvement - This may be related to the idea
LUCID DREAMING AND CONSCIOUSNESS 20
that REM sleep is pointed to correlate with a marked activation of limbic and paralimbic
structures, such as: the amygdala, the anterior cingulate cortex and the insula (Maquet et
al., 1996; Maquet et al., 2000; Nofzinger, Mintun, Wiseman, Kupfer, & Moore, 1997).
4. Altered mnemonic processes - Memory appears to be altered for the dream and within
the dream, and if the dreamer does not wake up, most dreams usually are lost forever,
probably not registered in memory (Nir & Tononi, 2010). Even if the dreamer awakes,
the memory rapidly vanishes in what concerns the greater details, if not written down or
recorded (Nir & Tononi, 2010). The hypo-activity of the pre-frontal cortex, which seems
to be also implicated in mnemonic processes, may have an important role in dream
amnesia (Braun et al., 1997, 1998; Maquet et al., 1996; Nofzinger et al., 1997).
In what concerns the neurophysiology of dreaming and waking consciousness, LaBerge
(2010) claims that dreaming can be ascertained as the special case of perception without the
constraints of external sensory input, as perception can be understood as the special case of
dreaming constrained by sensory input. No matter how one looks at it, conceptualizing
dreaming may be central for conceptualizing consciousness (LaBerge, 2010).
Nevertheless, to most lay-persons who experience agency and voluntary control of
action during waking, it may be probably clear that dream consciousness is somewhat limited.
Even so, waking consciousness may not be that different from dream consciousness, and the
main difference may reside in the absence of meta-cognition in non-lucid dreams. In turn, lucid
dreams are said to be a remarkable phenomena, in which one can regain meta-cognition inside
the dream scenario (Spoormaker et al., 2010).
As seen so far, and picking up some previously mentioned information for reasoning
purposes, cognitive neuroscience of dreaming proposes pre-frontal deactivations observed in
REM sleep as the cause of the cognitive limitations experienced in non-lucid dreaming (Hobson
& Pace-Schott, 2002; Nir & Tononi, 2010; Schwartz & Maquet, 2002; Spoormaker et al., 2010).
LUCID DREAMING AND CONSCIOUSNESS 21
Brain regions become selectively deactivated when compared to waking state, such as the
DLPFC and the precuneus, and others become more activated, such as the limbic and
paralimbic systems (Braun et al., 1997; Muzur et al., 2002). Neuroimaging PET studies
(Kajimura et al., 1999; Maquet et al., 1997; Nofzinger et al., 2000) and quantitative EEG
studies (Borbély, 2001; Finelli, Borbély, & Achermann, 2001; Werth, Achermann, & Borbély,
1997), have shown DLPFC selectively deactivating with the deepening of NREM sleep (Hofle
et al., 1997), and maintaining those selective deactivations during REM sleep (Nofzinger et al.,
1999). In waking state, this area seems to correlate with executive abilities such as expectancy
and working memory (Maquet et al., 2005; Muzur et al., 2002).
In lucid dreaming state, the previously deactivated DLPFC is proposed to re-activate,
and empirical evidence supporting this notion was put forward by Voss and colleagues (2009).
Their findings seem to indicate that when lucidity settles in, it is accompanied by a shift in EEG
power, especially in the 40 Hz range in frontal regions, with a larger EEG coherence in
frontolateral and frontal areas (Voss et al., 2009 – this experiment will be analysed in a more
detailed manner in Part III, sub-section 2). Through the use of fMRI, a higher activation has
also been proposed in frontal, temporal, and occipital regions in lucid dreams when compared to
non-lucid ones (Wehrle et al., 2005, 2007). As a result, it has been suggested that lucid
dreaming associates with pre-frontal re-activations (Hobson, 2009a; Hobson et al., 2000;
Karim, 2010; Spoormaker et al., 2010; Tononi, 2009; Voss et al., 2009).
Lucid dreaming may be characterized as a state that includes many aspects of
wakefulness state, such as: meta-cognitive abilities, memory, volition, fully realized agency, and
full awareness of current state, even though some degree of volitional behaviour can be
observed during non-lucid REM sleep (Dresler et al., 2014a; Takahara, Nittono, & Hory, 2006).
Lucid dreaming may be an excellent example of wake-like cognition in dreams, in the way that
it seems characterized by meta-cognitive insight and heightened levels of cognitive clarity
LUCID DREAMING AND CONSCIOUSNESS 22
(Noreika, Windt, Lenggenhager, & Karim, 2010). These particular aspects are being mentioned
for more than a century now, since the lucid dream phenomenon has been approached in a more
methodic and scientific way (Brown, 1934; Green, 1968; LaBerge, 1980; Van Eeden, 1913).
Nevertheless, lucid dreaming does not appear to be an all-or-nothing phenomenon, and
it may occur in different degrees, as in a continuum of subjectively experienced lucidity
(Dresler et al., 2014a; Moss, 1986; Noreika et al., 2010). This continuum may stretch from
varying degrees of lucidity (Moss, 1986), from pre-lucid dreams or reflections to lucid control
dreams (Barrett, 1992; Dresler et al., 2014a; Kahan & LaBerge, 1994). It was already
hypothesized in the 1980s that the awareness found in non-lucid dreams could be the beginning
of partial lucidity (Moss, 1986), and that lucidity could in itself be seen as changing
quantitatively along a continuum (Tart, 1985).
Even taking into account that, in practice, lucid and non-lucid dreams seem to be part of
a continuum, and do not appear to be two static and separate states, with the purpose of
characterizing lucid dreams, comparisons between non-lucid and lucid dream reports were done
in the past. One good example of this is a major review done in 1988 by Gackenbach, which
used the content of lucid and non-lucid dreams originating from dream diaries, questionnaires
filled out by the dreamers, and a few lucid dreams collected from sleep laboratories (LaBerge &
Gackenbach, 2000; Gackenbach, 1988). The material was then explored by content analysis,
leading the author to conclude that, when compared to non-lucid dreams, lucid ones presented,
on the average, more auditory and kinaesthetic dream sensations, more sense or higher level of
control, and fewer dream characters (LaBerge & Gackenbach, 2000; Gackenbach, 1988).
A few years later, in 1993, Levitan and LaBerge (as cited in LaBerge & Gackenbach,
2000) analysed self-rated content scales from six hundred and ninety-nine reports coming from
fifty-two veteran lucid dreamers (N = 52). When compared with non-lucid dreams, lucid ones
presented significantly higher levels of control, more positive emotions, higher levels of visual
LUCID DREAMING AND CONSCIOUSNESS 23
vividness, clarity of thinking, physical activity, and changes of scene (LaBerge & Gackenbach,
2000). Nevertheless, the authors pointed out that the sample was biased, as it recruited only
members of the Lucidity Institute. In what relates flying dreams, Barrett (1991) mentions that
these dreams are more likely to be reported by lucid dreamers and, when occurring in the same
dream, lucidity seems to precede flight (Barrett, 1991).
The contemporaneous approach to characterize lucid dreams is being done through face-
to-face and online surveys. These surveys aim to obtain broad and representative samples, from
which empirical findings on lucid dreaming, such as: prevalence, frequency, and typical
contents, are produced.
Schredl and Erlacher (2011) studied the frequency of lucid dreaming in a representative
German adults sample (N = 919), through a consultant that conducts surveys. All the
participants were contacted and interviewed at home, utilizing an eight-point rating scale (0 =
never, 1 = less than once a year, 2 = about once a year , 3 = about 2 to 4 times a year, 4 = about
once a month, 5 = about 2 to 3 times a month, 6 = about once a week, and 7 = several times a
week), that included one question: ”How often do you experience so-called lucid dreams (see
definition)?” (Schredl & Erlacher, 2011, p. 105); and one definition: ”During lucid dreaming,
one is, while dreaming, aware of the fact that one is dreaming. It is possible to wake up
deliberately, to control the dream action, or to observe passively the course of the dream with
this awareness.” (Schredl & Erlacher, 2011, p. 105). Dream recall frequency was also measured,
using a seven-point rating scale developed by Schredl (2004), along with socio-demographic
variables (age, sex, education, income, marital status, and population of place of residence).
According to the authors, the majority of respondents were infrequent lucid dreamers, whereas
about 20,1% were frequent lucid dreamers (frequency ≥ once per month) (Schredl & Erlacher,
2011).
Table 1 (next page) gives a full overview of the lucid dream frequency. All in all, and
LUCID DREAMING AND CONSCIOUSNESS 24
according to the study results, it would seem that about 51% of the German general population
has experienced a lucid dream at least once in their lives. Moreover, dream recall frequency
positively correlated with lucid dream recall frequency, even though the percentage of lucid
dreams compared to all recalled dreams was only 7,5%. Socio-demographic variables seem to
have no correlation with lucid dream frequency (Schredl & Erlacher, 2011). Interestingly
enough, the positive correlation between lucid dream frequency and dream recall frequency
seems to be an important one, and has been mentioned by previous studies (Blackmore, 1982;
Schredl & Erlacher, 2004; Watson, 2001).
In a more recent approach, Stumbrys and colleagues (Stumbrys, Erlacher, Johnson, &
Schredl, 2014) conducted an online survey to collect more extensive data on the
phenomenology of lucid dreaming. This included lucid dream origination, duration, active or
passive participation in the dream, planned actions for lucid dreams, and other
phenomenological aspects, in relation to participants age, gender, and lucid dream frequency.
Besides this, the authors also aimed to explore whether there were any differences relating
phenomenology between those who started having lucid dreams naturally, and those who
learned lucid dreaming deliberately. The sample for this study included six hundred and eighty-
LUCID DREAMING AND CONSCIOUSNESS 25
four participants (N = 684, 406 female and 278 male, age range: 10 to 74 years), who
completed an online questionnaire about lucid dreams.
According to the authors (Stumbrys et al., 2014), the online questionnaire was posted on
a German lucid dreaming Web site (http://www.klartraum.de), and was available in the first
seven months of 2004. The survey was anonymous, but an e-mail was asked, in an attempt to
minimize the risk of multiple responses. It included questions on biographical data and sixteen
items, from which five were open-ended, regarding dreams and lucid dreams. Participants also
estimated their dream recall frequency, on the same seven-point rating scale (Schredl, 2004)
that had been used in the previously presented survey (Schredl & Erlacher, 2011). Likewise,
lucid dreams frequency was evaluated on an eight-point scale (nightmare and creative dreams
were also evaluated), accompanied by a short definition of lucid dream: ”In lucid dreams, one
has awareness that one is dreaming during the dream. Thus, it is possible to wake up
deliberately, or to influence the action of the dream actively, or to observe the course of the
dream passively” (Stumbrys et al., 2014, p. 193).
According to Stumbrys and colleagues (2014), participants who claimed having had a
lucid dream at least once (N = 571), were asked additional questions about their lucid dreams,
such as:
Age of first lucid dream occurrence
By what means first lucid dream occurred
▪ Spontaneously
▪ Through deliberate training
▪ During relaxation techniques, for instance meditation or yoga
Estimation of average duration of lucid dreams (in minutes)
Descriptions of two possible continuations of lucid dreams were given (passive and
LUCID DREAMING AND CONSCIOUSNESS 26
active), and an estimation was requested (in percentages), of how often a passive or
active attitude was taken, in the lucid dreams
If actions had ever been tried (e.g., to fly, to speak with dream characters) in the lucid
dreams that had been planned in wakefulness state, and if so:
◦ Provide an approximate number of such efforts
◦ List the types of the planned actions attempted to accomplish
◦ Estimate the percentage of:
▪ How many intended actions in wakefulness were recalled in the lucid dreams
▪ How many of such recalled intents were successfully completed in the lucid
dreams
◦ Reasons for unsuccessful trials
On this survey, conducted by Stumbrys and colleagues (2014), the descriptive data
reveals that from the five hundred and seventy-one participants (N = 571) reporting having had
at least one lucid dream, 60,2% were frequent lucid dreamers (frequency ≥ once per month).
The mean age for the first lucid dream is 14,8 ± 7,8 years, and an average of 3,4 ± 5,6 is
reported. Moreover, 83,4% of first lucid dreams are said to be spontaneous, and happen as early
as age three, but are most likely to happen in the 12-14 age range, and much less likely to occur
after age 25. The mean duration of a lucid dream is estimated to be about 13,9 ± 13,4 minutes,
and lucid dreamers note that they are more likely to take an active role (56,3% ± 32,5%) in the
development of the dream plot, than a passive one. A majority of participants (58,9%) indicate
attempting to accomplish some waking intentions in their lucid dreams, averaging five
intentions per lucid dream. These intentions most often translate into actions impossible in the
wakefulness state, such as flying, which is the most popular one. Lucid dreamers seem to recall
almost half (48,5%) of their waking intentions inside the lucid dream, and less than half of those
recalled intentions (44,1%) are successfully carried out (Stumbrys et al., 2014).
LUCID DREAMING AND CONSCIOUSNESS 27
Relating to the effects of gender, age and lucid dream frequency, the authors (Stumbrys
et al., 2014) results indicate that women are more likely to be spontaneous than learned lucid
dreamers, have longer lucid dreams, but are less likely to take an active role in the development
of the dream plot, when compared to men. Furthermore, when predicting lucid dream
phenomenology, the frequency of lucid dreaming seems to be an important factor. Higher
frequency of lucid dreaming associates with an earlier occurrence of the first lucid dream, with
longer lucid dreams, with a higher likeness to try waking intentions in lucid dreams, with a
higher remembrance of such intentions, and a higher rate of accomplishment of those same
intentions. When comparing to spontaneous lucid dreamers, trained ones have shorter lucid
dreams, but a higher probability of taking an active role in the development of the lucid dream
plot, and are also more likely to try some waking intentions in their lucid dreams (Stumbrys et
al., 2014).
In the same line, a very recently published longitudinal study from Schredl and Göritz
(2015) analysed changes in lucid dream frequency in two online surveys with a three-year
period interval between them (concomitant with dream recall and nightmare frequency). An
eight-point scale was used to measure the lucid dreaming frequency (0 = never, 1 = less than
once a year, 2 = about once a year , 3 = about 2 to 4 times a year, 4 = about once a month, 5 =
about 2 to 3 times a month, 6 = about once a week, and 7 = several times a week), and a
definition adopted from a previous study (Schredl & Erlacher, 2004) was presented for the
scale:
”In a lucid dream, one is aware that one is dreaming during the dream. Thus it is
possible to wake up deliberately, or to influence the action of the dream actively,
or to observe the course of the dream passively.” (Schredl & Göritz, 2015, p. 3).
The study had a relatively large sample (N = 1,281) answering both surveys. The authors
consider the percentage of persons with no changes or small changes (±1) very high, as in
LUCID DREAMING AND CONSCIOUSNESS 28
63,39%, but nevertheless point out a decline in lucid dream frequency correlating with age
during adulthood, also stating that it is not a representative sample, even though it has a broad
age range (Schredl & Göritz, 2015). Table 2 (below) gives an overview of the results.
Lucid dreams are also thought to correlate with phasic REM (LaBerge & Gackenbach,
2000). In 1986, LaBerge and colleagues (LaBerge, Levitan, & Dement, 1986) picked up
physiological data from seventy-six laboratory lucid dreams of thirteen participants. This data
was used to compare eye movement activity, heart rate, respiration rate, and skin potential
activity, of lucid and non-lucid segments of REM periods. According to the authors, the lucid
segments of the REM periods exhibited significantly higher levels of physiological activation
than the preceding segments of non-lucid REM from the same REM periods. Also, REM
periods in which lucid dreams occurred were more activated than the ones in which it did not
occur (LaBerge et al., 1986). Furthermore, Hoffmann's reflex (H-reflex) amplitude was lower
during lucid REM (Brylowski, Levitan, & LaBerge, 1989), even though one must add that there
are limitations in the way H-reflex studies' results may be interpreted (Misiaszek, 2003). Taking
all this together, Laberge and Gackenbach (2000) suggest lucid REM as ”a paradoxically
deepened state of REM, with increased phasic activation and suppression of spinal reflexes”
LUCID DREAMING AND CONSCIOUSNESS 29
(Laberge & Gackenback, 2000, p. 160).
Lucid dreams are pointed out to occur mainly late in the sleep cycle (LaBerge &
Gackenbach, 2000; LaBerge et al., 1986; Van Eeden, 1913), almost exclusively during REM
sleep (LaBerge & Gackenbach, 2000; LaBerge et al., 1986). It also seems to be a learnable skill
and practice with some inductive techniques is thought to make motivated individuals, with a
good dream recall frequency (≥ once a week), to become lucid more easily (LaBerge, 1980;
LaBerge & Gackenbach, 2000 – induction techniques are analysed in more detail in Part III,
sub-section 1).
Another intriguing subject is the relationship between time in lucid dreams and real
time, that is, how time elapsed while executing cognitive tasks or motoric actions in lucid
dreams differs from the time elapsed executing the same tasks and actions in wakefulness.
Earlier studies have proposed an equivalence of time for counting in lucid dreams and in
wakefulness, but about 40% more time to perform a motor task (walking, gymnastics, squats) in
lucid dreaming (Erlacher & Schredl, 2004, 2008; LaBerge, 1985). Notwithstanding, more recent
studies propose that, despite the longer absolute durations for tasks involving motor activity, the
relative durations remain the same, thus also proposing that lucid dreaming can be used by
athletes the same way mental rehearsal is used in wakefulness, that is, to increase performance
(Erlacher, Schädlich, Stumbrys, & Schredl, 2014; Erlacher & Schredl, 2010). Erlacher and
colleagues (2014) speculate that motor tasks prolonged durations in lucid dreams might relate to
the lack of muscular feedback, or REM sleep slower neural processing. More research is needed
to clarify this particular aspect.
In accordance with Dresler and colleagues (2014a), contrasting with coma-wake,
anaesthesia-wake, or sleep-wake comparisons, the comparison between non-lucid and lucid
dreaming may be a fundamental key for understanding the neural correlates of consciousness,
since there is no major shift in vigilance state as defined by formal neurophysiological criteria,
LUCID DREAMING AND CONSCIOUSNESS 30
as lucid REM sleep is still REM sleep according to the American Association for Sleep
Medicine (AASM) sleep scoring benchmark (Dresler et al., 2014a; Iber, Ancoli-Israel, Chesson,
& Quan, 2007).
3. Human dreams: delusional hallucinations or creative imaginations?
Some authors point out that to create dream egos in dream worlds one needs only his
imagination, as in the ability to fashion mental images and to envision other worlds (Schredl,
2010; Thompson, 2015b). This may mean that, if dreaming has a source in imagination, the
dominant idea of dreams as delusional hallucinations may be, at least, an oversimplification
(Schredl, 2010). According to Thompson (2015b), in a non-lucid dream, one tends to lose
awareness and identify with the dream ego as the ”I”, whereas in a lucid dream, one regains the
awareness of the imagination consciousness.
Along the same lines, Kuiken (2010) and Brylowski (2010) indicate that non-lucid
dreaming may not be a model for psychopathology, as this would endanger a conception of
dreaming that respects its distinctive form of cognitive functionality. On the other hand, it may
well be a model of musical improvisation or involuntary poetry, than one of psychopathology.
In essence, formally defining dreaming as an hallucination may not be helpful for this field of
study (Brylowski, 2010; Kuiken, 2010). Moreover, Schredl (2010) adds that an outside
perspective on dreaming is when one uses the definition of hallucination for dreaming, and this
may not be useful because the brain state during hallucinations seems to be quite different from
the brain state during dreaming (Schredl, 2010).
In contrast, a very recent review by Dresler and colleagues (2015) clearly states that
cortical areas active during lucid dreams exhibit remarkable overlap with brain regions impaired
in psychotic patients. This would bring empirical support to the notion of lucid dreaming as a
model for insight into the psychotic state, inside the conceptualization of non-lucid dreaming as
LUCID DREAMING AND CONSCIOUSNESS 31
a model for psychosis. The later concept is in itself based on the notion that non-lucid dreaming
and psychosis share the same characteristics, such as: hallucinations, delusions, bizarre
experiences, disorganized thought, emotional intensifications, and lack of insight into current
state (Dresler et al., 2015). As non-lucid dreams can become lucid, the authors propose that
insight into his own condition can be improved in psychotic patients, by studying the ways
insight establishes itself in lucid dreams, bringing with it lucidity into the current state of the
individual. This is a very interesting avenue of research, which may lead to practical clinical
applications of lucid dream research. Dreams and lucid dreams may after all be a model for
psychopathology.
Erlacher and Chapin (2010) pick up the virtual reality hypothesis of dreaming and also
propose REM dreams as a kind of simulation of the real world on a higher cognitive level. The
dream actions would function as a neural simulation, which would imply that dreaming an
action could alter the waking performance of that action, improving it. In the authors opinion,
autonomic responses during dreams of physical activity parallel autonomic responses during
actual exercise, and the timing of both actions, the time that elapses to perform the actions in
the dream and in the waking state is also related. The authors also point out lucid dreams as an
ideal moment to practice those actions, for improved performance, as it offers the potential to
practice with a body complete with kinaesthetic sensations, in an environment that appears to be
experienced by the dreamer with the same vividness and realism of the waking experience,
which would work out better than mental practice and modern virtual reality simulators
(Erlacher & Chapin, 2010). This line of work seems also to go against the idea of dreams as
delusional hallucinations, at least in a strict sense.
On the other hand, the term virtual reality experience can be misleading, as the same
virtual reality scenario can be experienced by several people, whereas dreaming is generated
within the person's brain and cannot be perceived by others (Schredl, 2010). Moreover, some
LUCID DREAMING AND CONSCIOUSNESS 32
authors state that ”delusions” and ”hallucinations” seem to be part of the ordinary sleeping
experience, entirely normal in that context, which may help to defuse the negative connotations
of the words (Brooks & Vogelsong, 2010).
Curiously enough, some of the areas of the brain that are activated and deactivated
during non-lucid REM dreaming have been pointed out to be involved in the spontaneous
generation of music, such as jazz improvisation, which were preliminarily characterized by
deactivation of the DLPFC and simultaneous activation of the MPFC (Limb & Braun, 2008). In
Kahn and Gover's (2010) opinion, this attenuation of the DLPFC may imply a deregulation of
the contents of consciousness, which might benefit creative intuition, allowing unfiltered,
unconscious, or random thought and sensations to emerge, and this may account for some of the
innovation and creativity in non-lucid dreams where the DLPFC is also deactivated.
Thompson (2015b) conveys the concept of creative imagination in a quite curious way:
“You don't get a being with a sense of self by taking a hallucinating brain and
taking on some sensory inputs and motor outputs. You get a being with a sense of
self by taking a brain with a capacity for imagination – for imaging its past and
future – and embedding it within a sensing and moving body.” (Thompson, 2015b,
p. 188)
All in all, among researchers there seems to be a disagreement on the way dreams, non-
lucid and lucid, may be characterized. It would seem that, in a sense, human dreams can both be
delusional hallucinations and creative imaginations, depending on what lane of research one is
in, exactly. Several research routes are apparently open, and more studies are needed to pave
and strengthen those same lanes.
In the next section, the cognitive neuroscience of lucid dreaming is discussed, in what
concerns the late twentieth century conceptions of lucid dreams, in a very short way, to the most
relevant studies pertaining the aim of this theoretical investigation.
LUCID DREAMING AND CONSCIOUSNESS 33
Part III – The cognitive neuroscience of lucid dreaming
Research in the 1960s and 1970s posted lucid dreaming experiences in the frequent
transitory arousals detected during REM sleep, and these micro-awakenings were proposed to
be its physiological basis (LaBerge, 1990; LaBerge & Gackenbach, 2000). Nevertheless, it
would seem that one lone researcher suggested that lucid dreams were occurring during the
paradoxical phase of sleep, as REM was called, like any other dreams (Green, 1968; LaBerge
& Gackenbach, 2000). These speculations lacked empirical evidence to support them, and a
physiological way to mark the exact time the lucid dream was taking place was in need
(LaBerge & Gackenbach, 2000). Already in the 1960s it had been found that, in many dream
reports, the eye movements recorded during REM corresponded to the direction the subjects
had reported (LaBerge & Gackenbach, 2000; Roffwarg, Dement, Muzio, & Fisher, 1962).
Knowing this, probably it would be possible to use the dreamer volitional capabilities during
the dream to make a pre-arranged eye movement signal, marking the exact time they became
lucid (LaBerge & Gackenbach, 2000).
1. The use of lucid dreams in cognitive neuroscience research
As mentioned before, in lucid dreams the dreamer appears to possess a consciousness
comparable to waking state, regarding coherence, clarity and cognitive complexity. In the past,
it was questioned if these experiences were happening during sleep, or during brief
hypnopompic periods of wakefulness (LaBerge, 1990). Attempting to answer this question,
LaBerge and colleagues (1981) designed an experiment intended on determining the
physiological conditions in which lucid dreaming occurs. The authors took into account lucid
dreaming definition, reasoning that if dreamers became aware they were dreaming, maybe they
could also signal in their dream, and that signal probably would have a physiological correlate
LUCID DREAMING AND CONSCIOUSNESS 34
(LaBerge & Gackenbach, 2000; LaBerge et al., 1981).
LaBerge and colleagues (1981) experiment had five subjects (N = 5), trained in a
cognitive technique called Mnemonic Induction of Lucid Dreams (MILD), and selected for
their claimed ability of having lucid dreams on demand. The participants were studied in a sleep
laboratory for two to twenty non-consecutive nights. Standard PSG recordings were done,
including EEG, EOG, and chin, left and right wrist EMG. To mark the onset of a lucid dream,
the subjects produced a pre-arranged signal with dreamed eye shifts, which consisted of
extreme horizontal movements in a pattern left-right-left-right (L-R-L-R), that translated in the
EOG register. In total thirty-five lucid dreams were reported after spontaneous wakening from
different stages of sleep: REM in thirty-two cases, NREM N1 in two cases, and during the
transition from NREM N2 to REM in one case. The participants reported signalling during
thirty of these lucid dreams (LaBerge et al., 1981).
After each recording, according to the authors, the reports alluding to signals and the
respective PSG were reviewed by a judge unaware of the times of the reports. The role of the
judge was to determine whether one (or none) of the PSG epochs had a correspondence with the
reported lucid dream signal. In twenty-four of the aforementioned thirty-five cases, the judge
was capable of selecting the appropriate thirty-seconds epochs, out of about a thousand per
PSG, based on the correspondence between reported and observed signals. The chance
probability of this selection ratio was said to be astronomically small (LaBerge et al., 1981).
Since then, similar experiments were done in several other laboratories, providing strong
evidence to the idea of lucid dreaming as a sleep phenomenon (Armstrong-Hickey, 1988;
Dresler et al., 2012; Fenwick, Schatzman, Worsley, Adams, Stone, & Baker, 1984; Ogilvie,
Hunt, Kushniruk, & Newman, 1983; Voss et al., 2009).
With this said, one can question how to know that the subjects were really asleep when
the pre-arranged signal registered in the EOG? The answer appears to be straightforward: the
LUCID DREAMING AND CONSCIOUSNESS 35
subjective lucid dream accounts and the physiological sleep measures coincided, that is, ”all
signals associated with lucid dream reports occurred during epochs of unambiguous REM sleep
scored according to the standard criteria” (LaBerge et al., 1981, p. 729). The two main
conclusions arising from LaBerge and colleagues (1981) study were: first, lucid dreaming
seems to ensue mainly during REM sleep, and second, the results point out to the possibility of
lucid dreamers signalling intentionally to the outside world from the dream world while
dreaming (LaBerge et al., 1981). These two inferences opened the door for a new approach to
dream research: it was now possible to carry out experiments in which subjects could mark the
exact time of occurrence of specific lucid dream events. In turn, this allowed for the derivation
of psycho-physiological correlations and methodical testing of hypothesis (LaBerge &
Gackenbach, 2000; LaBerge et al., 1981).
According to some authors (LaBerge & DeGracia, 2000; LaBerge & Gackenbach, 2000;
LaBerge et al., 1986), the use of lucid dreams in cognitive neuroscience research requires the
acquaintance or familiarity with several methodological issues, such as:
1. Subjective reports and introspection are known to provide the most direct accounts of
the contents of consciousness, but they are difficult to verify objectively, and
introspection is very far from an unbiased, direct or error-free process of observation
(LaBerge & Gackenbach, 2000). In a experiment, it is of utmost importance that
subjects clearly understand the concept of lucid dreaming, as in the inclusion of a
recognition phrase in a sample lucid dream report (Snyder & Gackenbach, 1988).
2. The capacity for dream recall seems to be an excellent predictor of lucid dreaming
ability in untrained participants (Schredl & Erlacher, 2004; Snyder & Gackenbach,
1988).
3. When pinpointing lucid dreams, it would be important to take into account that it
probably associates with phasic REM, as it has been proposed that lucid segments of
LUCID DREAMING AND CONSCIOUSNESS 36
Signal-Verified Lucid Dreams (SVLDs) REM periods seem to be characterized by
higher levels of physiological activation, when compared with the preceding segments
of non-lucid REM from the same REM periods (Brylowsky et al., 1989; LaBerge &
Gackenbach, 2000; Laberge et al., 1986).
4. The extreme horizontal eye movement methodology (L-R-L-R) inside the dream, to
produce SVLDs, may be problematic, as it is not easily executed, and may lead to
awakenings, as this eye movement inside the dream is thought to affect what the subject
is seeing in the dream, disrupting the visual imagery (LaBerge & Gackenbach, 2000).
5. It is posited that SVLDs may start from an ongoing REM non-lucid dream, as in dream-
initiated lucid dream (DILD), or directly from a short awakening, as in wake-initiated
lucid dream (WILD). On average, two-thirds of lucid dreams are thought to be DILDs
and one-third WILDs (LaBerge & Gackenbach, 2000; Laberge et al., 1986), but this is a
preliminary figure, that needs expansion through further research.
6. Lucid dreams may end in four different ways: in awakening, by becoming a non-lucid
dream, by falling in NREM sleep, or in a false awakening (LaBerge & DeGracia, 2000).
Lucid dreaming is pointed out to be a learnable skill (LaBerge, 1980), and a variety of
techniques for the induction of lucid dreams have been developed. Stumbrys and colleagues
(Stumbrys, Erlacher, Schädlich, & Schredl, 2012), presented a taxonomy of lucid dream
induction methods taken from thirty-five studies, assessed for their methodological quality, and
systematically reviewed the evidence for the effectiveness of induction techniques. The authors
concluded that none of the techniques seem to induce lucid dreams reliably and consistently, but
some of them showed potential, according to their meta-analysis method. The expression lucid
dream induction refers to any means that aim to increase the frequency of lucid dreams, and the
authors defined three broad categories in an attempt to present an empirically based
classification of lucid dream induction techniques:
LUCID DREAMING AND CONSCIOUSNESS 37
1. Cognitive techniques that include all that is carried out to increase the likelihood of
achieving lucidity in a dream state by training cognitive skills, such as prospective
memory, self-reflection or intention. The techniques are: MILD (Mnemonic Induction of
Lucid Dreams), Reflection or Reality Testing, Intention, Tholey's Combined technique,
Auto-suggestion, Dream Re-Entry, Post-hypnotic Suggestion, and Alpha Feedback.
2. External stimulation techniques that include all types of stimuli possible to trigger
dream lucidity during REM sleep, by presenting a visual, auditory or tactile cue that
might be incorporated in the dream and recognized by the dreamer, such as: light
stimulus, acoustic stimulus, vibro-tactile stimulus, electro-tactile stimulus, and water
stimulus; or by specific activation, such as vestibular bodily stimulation.
3. Drug application methods that aim to alter cholinergic levels of the brain to enhance
lucidity in dreams, such as the application of an acetylcholine esterase inhibitor class
drug (Donepezil).
According to Stumbrys and colleagues (2012), in the realm of the cognitive techniques,
one promising induction method seems to be Tholey's combined technique, which has been
already tested in two studies with high methodological quality (Paulsson & Parker, 2006; Zadra,
Donderi, & Pihl, 1992) and incorporates elements of reflection, as in developing a reflective
frame of mind, intention, as in imagining being in a dream and recognizing it, and auto-
suggestion, as in suggesting oneself to become lucid when falling asleep. This technique seems
to increase significantly the frequency of lucid dreaming, especially for those previously
experienced with lucid dreams, and also to increase the frequency for the participants with no
previous experience, when compared with controls (Paulsson & Parker, 2006; Stumbrys et al.,
2012; Zadra et al., 1992).
Relating to external stimulation techniques, Stumbrys and colleagues (2012) point out
that some stimuli might be effective for lucid dream induction, such as light flashing on the
LUCID DREAMING AND CONSCIOUSNESS 38
eyes of a dreamer or an electrical impulse applied on the wrist during REM sleep. However, the
authors urge that these findings should be interpreted with caution, as the results were published
previously to the commercialization of the studied devices (DreamLight, DreamLink,
NovaDreamer, Dreamachine). Drug application methods seem to be intriguing, but very little
research has been conducted on the subject, thus more rigorous studies are needed (Sergio,
1988; Stumbrys et al., 2012).
When considering lucid dream induction research in general, one of the major issues is
to point out which valid criteria defines a successful induction. In sleep laboratory studies, the
valid criteria should be unambiguous predefined eye signals in the EOG register during REM
sleep, together with a dream report received immediately after awakening following signalling,
which would confirm lucidity and volitional eye signals (Stumbrys et al., 2012). The timing of
the dream report may be crucial, as to avoid impairing by sleep inertia, a transitional state
between sleep and wakefulness in which cognitive performance is pointed to be decreased
(Tassi & Muzet, 2000). These first-person subjective reports can be trusted, regarding
accurately conveying internal experiences in sleep, because the estimated time in dream report
correlates well with the time elapsed in REM sleep before the awakening (Windt, 2013). A very
illustrative case for this is the one presented by RBD, where muscle atonia is disrupted, and the
observed movements match the reported dream (Nir & Tononi, 2010).
Relating the probing of the neurobiology of dream contents, use of trans-cranial direct
current stimulation (tDCS) has been suggested, supported by the rationale that neuroimaging
studies solely allow correlative statements about the brain regions involved in a specific
behaviour (Karim, 2010; Noreika et al., 2010). TDCS allows for cathodal stimulation, which
hyper-polarizes neurons diminishing cerebral excitability, and anodal stimulation, which results
in increased cortical excitability (Nitsche & Paulus, 2000). Therefore, in what concerns the pre-
frontal hypothesis of lucid dreaming (Hobson, 2009a), it may be possible to apply anodal tDCS
LUCID DREAMING AND CONSCIOUSNESS 39
during REM sleep in order to activate the DLPFC and test if this external modulation of cortical
excitability induces lucidity, or increases lucid dream frequency, on the subject (Noreika et al.,
2010). Conversely, this can also be used vice versa, that is, inhibiting the DLPFC of veteran
lucid dreamers with cathodal stimulation, to discern if lucid dreaming would be prevented or
attenuated (Noreika et al., 2010). These possible findings could give causal support to the
correlative data obtained by neuroimaging studies, thus proving a predominant role of the
DLPFC in lucid dreaming (Karim, 2010; Noreika et al., 2010).
To summarize, researchers seem to be confident on experiments that couple first-person
reports with objective measures such as voluntary eye movements, which seems to be an
acceptable approach to access the phenomenology of the lucid dreaming brain. Meta-awareness,
probably one of the most conspicuous characteristic of human consciousness, is a subjective
experience and an entirely internal percept, but lucid dreams seem to present researchers with a
unique opportunity to combine introspection with a third person approach to the study of meta-
awareness in a state of known physiology, REM sleep dreaming (Voss, 2010). The scientific
investigation of lucid dreaming may hold the promise of returning psychology to its base in
introspection, now safeguarded with powerful third person tools, including quantitative rating
scales, quantitative EEG, and fMRI (Voss, 2010).
The next sub-section will deal with some of the most relevant contemporaneous
cognitive neuroscience research relevant for the purposes of this investigation.
2. Contemporary cognitive neuroscience research with lucid dreaming
In this sub-section, nine of the most recent and relevant studies on lucid dreaming, in
what pertains the aims of this theoretical investigation, will be analysed, in a more in-depth
fashion. These studies comprise a six-year span, from 2009 to 2015, except for the first one
presented, which is a pilot study from 2003, and has been included for its very interesting
LUCID DREAMING AND CONSCIOUSNESS 40
attempt on studying mind-body interactions with lucid dreaming.
Lucid dreaming may be a very useful tool indeed for the study of mind-body
interactions (Schredl, 2000). Erlacher, Schredl and LaBerge (2003) studied the physiological
responses to dreamed motor performance in REM lucid dreams, in a pilot study with a single
subject (N = 1) on EEG alpha band. The volunteer was a male (27 years old) with lucid
dreaming training, that spent three non-consecutive nights in the laboratory. The experimental
protocol included signalling the realization of being in a dream, by means of L-R-L-R pattern of
horizontal eye movements during the lucid dream. Afterwards, the subject would sit down in the
dream, again eye signal L-R-L-R to mark the beginning of left hand clenching, open and clench
the left hand four times, L-R-L-R eye signal to mark the end of left hand clenching and the
beginning of the right hand clenching, open and clench the right hand four times, and finally L-
R-L-R eye signal to mark the end of right hand clenching. Also, and as a reference sequence,
the subject was asked to count from zero to four, inside the dream, and to mark this sequence by
L-R-L-R eye signal in the beginning and in the end of the sequence. After the complete task, the
subject needed to awake himself up by means of focusing a spot in the dream, and afterwards
record the dream experience (Erlacher, Schredl, & LaBerge, 2003).
In this experiment (Erlacher et al., 2003), standard PSG were recorded, including 28-
channel EEG (expanded 10-20 system), horizontal and vertical EOG and chin EMG. According
to the authors, their preliminary results seem to point out to an association between hand
movements performed in a lucid dream, and corresponding activations of specific motor areas.
It was also pointed out a decrease in EEG alpha power over bilateral motor areas, while the
lucid dreamer executed left or right hand clenching, in contrast to dream counting (Erlacher et
al., 2003). The authors also point out that these results seem to support the hypothesis that the
same cortical areas are used for motor performance in waking and in lucid dreaming, and also
support the idea that dreamed movements are parallel to movements in waking (Erlacher et al.,
LUCID DREAMING AND CONSCIOUSNESS 41
2003). As such, it would seem the phenomenon of lucid dreaming provides an important
research paradigm for studying mind-body interactions (Erlacher et al., 2003). Nevertheless,
one must say that this is a preliminary study and, although very interesting, it has only one
participant. Replication with a large sample would be needed to further expand this knowledge.
In the same line, Voss and colleagues (2009) sought physiological correlates of lucid
dreaming, testing the hypothesis that the brain must change state if the mind changes state. The
rationale behind it stated that, if lucidity can be self-induced, similarly to a trainable skill
(LaBerge, 1980), this would constitute an opportunity to understand the brain basis of conscious
states, and how these states could be changed by voluntary intervention (Voss et al., 2009).
In this experiment (Voss et al., 2009), a group of twenty undergraduate psychology
students from Bonn University (Germany) took part in lucidity training sessions, on a weekly
basis. The authors do not specify what kind of lucidity training these subjects underwent.
Nevertheless, after four months of regular week training, six subjects claimed to be lucid more
than three times per week. Again, the authors do not specify how these claims were made, or
how they were verified. These six participants (N = 6) were invited to Frankfurt University's
sleep laboratory (Germany). Written consent for participation was given, and a fifty Euro
(€50,00) compensation per night was paid to each participant. It would seem that standard PSG
were recorded, with scalp EEG electrodes (placed at 19 positions; 10-20 system), EOG (taken
from the outer canthi of both eyes and supra-orbitally to the left eye), and EMG at the chin.
EEG was recorded for two to five nights per subject (Voss et al., 2009).
According to the authors (Voss et al., 2009), from the six subjects, three (one male aged
22 and two females aged 23 years) were each able to become lucid once in the laboratory
setting. These three recorded lucidity episodes seem to have occurred spontaneously, pointed by
the authors as a result of auto-suggestion. Subjects were trained to report lucidity by a two-set
of L-R-L-R horizontal eye movements, separated by a brief pause, and were also asked to
LUCID DREAMING AND CONSCIOUSNESS 42
repeat this pattern several times during the lucid dream. Lucidity was confirmed through
subjective free reports upon awakening (Voss et al., 2009).
The authors point out (Voss et al., 2009) that EEG power, averaged across all electrodes
as a function of frequency, seems to be REM-like in lucid dreaming in lower frequencies; and
appears to rise above REM sleep at higher frequencies, mainly in gamma waves, starting around
28 Hz and peaking at 40 Hz (Voss et al., 2009). These gamma rhythms, or oscillations in the
gamma frequency band of the EEG, are thought to be involved in the binding of neural events
that are spatially separated but temporally correlated, resulting in a unified perceptual
experience (Castro, Falconi, Chase, & Torterolo, 2013; Fries, Nikolić, & Singer, 2007;
Niedermeyer & Da Silva, 2004). This mechanism seems to explain the extensive interactions
between various regions of the cerebral cortex during cognitive processes or motor functions
(Castro, et al., 2013; Fries et al., 2007; Niedermeyer & Da Silva, 2004). The extent of these
interactions can be examined by means of a mathematical algorithm called “coherence”, which
reflects the strength of functional interactions between cortical areas (Castro, et al., 2013; Fries
et al., 2007; Niedermeyer & Da Silva, 2004).
Taking the authors' words (Voss et al., 2009), higher delta and theta activity and lower
alpha power appear to be characteristic of lucid dreaming, and this seems to evince that this
phenomenon occurs in a REM sleep state. The increase in higher frequency power occurring
during lucid dreaming compared to REM sleep apparently shows the difference between both
states, and seems to highlight lucid dreaming as a unique state of sleep (Voss et al., 2009).
Moreover, the findings on power seem to suggest that lucidity may be occurring in a hybrid
state, as the authors put it, with some features of REM sleep, as in delta and theta waves, and
some of waking, as in gamma waves. Likewise, the data obtained is claimed to show lucid
dreaming as a hybrid state of consciousness, with definable and measurable differences from
waking and from REM sleep, mainly in frontal areas of the brain (Voss et al., 2009). Also, the
LUCID DREAMING AND CONSCIOUSNESS 43
frontal and frontolateral regions of the brain seem to have a central role in gaining lucid insight
into the dream state and in gaining volitional control (Voss et al., 2009).
This study is commonly presented as a breakthrough, and cited many times (times cited:
83 from Web of Science core collection in June 2015) on subsequent literature in lucid
dreaming, but a major drawback is that the findings are build upon three lucid dreams, each
from one of three subjects. This may be a weak sample from which to retrieve so many
conclusions, and replication studies are needed.
In another study, Voss and colleagues (Voss, Frenzel, Koppehele-Gossel, & Hobson,
2012) proposed a link between the natural occurrence of lucid dreaming and brain maturation.
This link is primarily based on previous reports of an inverse relationship between age and
frequency of lucid dreaming, higher age seems to be linked with less frequency (this link is also
mentioned in Part II, section 2 of this thesis) (Blackmore, 1984; Schredl & Erlacher, 2004,
2011; Watson, 2001). This study sample had six hundred and ninety-four participants (N = 694;
346 female, 348 male; age range: 6 to 19 years old), all students from German primary and
secondary schools. The sample was representative for secondary school type attendance in
Germany (Voss et al., 2012).
As mentioned by Voss and colleagues (2012), the procedure consisted of one-on-one
interviews conducted by trained graduate students of the Psychology Department of Bonn
University (Germany). The participants were provided with a detailed account of lucid
dreaming, and ample time was given to make sure they understood the concept. Afterwards,
subjects were interviewed with a protocol containing three parts: four sleep-related questions,
seven dream-related questions, and two final questions to test their suggestibility. If a lucid
dream was reported, the interviewer would request an example of such a dream plot, in the
narrative form (Voss et al., 2012; please refer to Appendix A for the interview questions).
Relating to lucidity frequency, 51,9% (N = 360) of the total participating students
LUCID DREAMING AND CONSCIOUSNESS 44
reported having had at least one lucid episode in their life. From these, only 25% (N = 91) said
to experience a lucid dream once a month or more (Voss et al., 2012). The results are said to
show that lucid dreaming appears to be quite pronounced in young children, and its incidence
rate appears to drop at about sixteen (Voss et al., 2012). With this in mind, the authors presented
preliminary evidence that the state of lucid dreaming may be said to correlate with brain
maturation during childhood and early adolescence (Voss et al., 2012). Reported lucidity seems
to occur in greater number in the young and in those who are intellectually more capable (Voss
et al., 2012).
In addition, controlling the dream plot is mentioned to occur in only one third of the
lucid dreams, which seems to point out that plot control may not be as strong a defining
characteristic of lucid dreaming as lucid insight. Students claiming to have plot control also
reported a higher lucid dreaming frequency (Voss et al., 2012). The authors hypothesize that
lucidity could be a transient state during brain maturation, that is normally lost in adulthood but
still accessible through training (Voss et al., 2012). The frequency of dream recall seems to be
significantly correlated with frequency of lucid dreams, suggesting that the ability to remember
one's dreams facilitates lucid dreaming or the memory of it (Voss et al., 2012), in line with
previously mentioned by Schredl and Erlacher in 2011 (refer to Part II, sub-section 2 for
details).
Also in 2012, Dresler and colleagues presented a study that aimed to investigate the
neural correlates of lucid dreaming by contrasting lucid versus non-lucid REM sleep, using a
combined EEG-fMRI approach. The sample for this study was comprised by four experienced
lucid dreamers (N = 4; all male; age range: 27 to 32 years), that had been recruited through
internet advertisements. All participants were screened for medical conditions contrary to study
aims, gave written consent for participation, and were paid for participating (the amount is not
revealed). Subjects slept in a MRI scanner with simultaneous PSG monitoring during two to six
LUCID DREAMING AND CONSCIOUSNESS 45
nights each (Dresler at al., 2012).
The experiment protocol in this study (Dresler et al., 2012) indicated that, immediately
after achieving lucidity in their dream, the subjects should move their eyes L-R-L-R, and
afterwards clench their left hand for about ten seconds, give the L-R-L-R signal again, clench
the right hand, and so on, as long as possible. The fMRI epochs showing lucid dreaming were
defined by the prearranged L-R-L-R signals in the EOG. Lucidity was assumed to start with the
first L-R-L-R signal, indicating also the onset of the dreamed hand movements. All participants
reported experiencing lucidity at least once, but only one subject had two SVLDs with four or
more consecutive sets of L-R-L-R signals (Dresler et al., 2012).
As in a previous study (Voss et al., 2009), Dresler and colleagues' (2012) experiment is
said to have observed increased activity in the right DLPFC during lucid dreaming. This
specific area is stated to associate with self-focused meta-cognitive evaluation (Schmitz,
Kawahara-Baccus, & Johnson, 2004). Other areas found to be strongly activated, when
compared with non-lucid REM sleep, were the precuneus, the bilateral cuneus, the parietal
lobes, and the pre-frontal and occipito-temporal cortices (Dresler et al., 2012).
The strongest increase in activation was reported to be in the precuneus (Dresler et al.,
2012), a brain region thought to be involved in self-referential processing, particularly first-
person perspective and experience of agency (Cavanna & Trimble, 2006). Interesting enough,
the bilateral cuneus and the occipito-temporal cortices are pointed as part of the ventral stream
of visual processing, which in turn appears to participate in several aspects of conscious
awareness in visual perception (Rees et al., 2002). Moreover, the activation of the DLPFC in
association with the parietal lobes might reflect working memory demands related to task
performance (Smith & Jonides, 1998), as in the intentional movement of the eyes and clenching
of the hands in the SVLDs (Dresler et al., 2012).
In neuroanatomical terms, all the regions found to activate in Dresler and colleagues
LUCID DREAMING AND CONSCIOUSNESS 46
(2012) experiment belong to the neocortex, which is an exclusively mammalian part of the
cortex, and is larger and more developed in humans than in other primates (Thompson, 2015b).
These areas seem to form an intentional control system for cognition and decision making - a
frontoparietal control system -, which links brain networks that support the ability to pay
attention to the outside world with other networks related to long term memory, and with the
ability to think about oneself, in a way as to remember one's personal past and project oneself
into an anticipated future (Vicent, Kahn, Snyder, Raichle, & Buckner, 2008; Thompson, 2015b).
All in all, Dresler and colleagues (2012) experiment is a very interesting one indeed, in
the way it places the lucid dream under the MRI machine, so to speak. The conundrum here is
that, starting from a very small sample the study became a case study in the end, and can only
be used, at best, as preliminary evidence with functional data.
In 2013, Stumbrys and colleagues (Stumbrys, Erlacher, & Schredl, 2013) applied tDCS
in an attempt to manipulate the activation of the DLPFC during REM sleep, with the aim of
increasing dream lucidity. This was based on the rationale that increased brain activity over
frontal regions during REM sleep is thought to associate with lucidity in dreams (Dresler et al.,
2012; Voss et al., 2009). The intention was to go beyond the correlational data, experimentally
manipulating the activation of the pre-frontal brain cortex, thus testing the neurobiological basis
of dream lucidity (Karim, 2010; Noreika et al., 2010; Stumbrys et al., 2013).
As previously specified (please refer to Part III, sub-section 1), tDCS involves the
uninterrupted administration of weak currents (1mA) through a pair of surface electrodes,
cathode and anode, affixed to the scalp (Nitsche & Paulus, 2000), and is based on the notion
that cerebral excitability diminishes with cathodal stimulation, which is thought to hyper-
polarize neurons, whereas anodal stimulation increases cortical excitability (Nitsche et al.,
2008). This method, unlike trans-cranial magnetic stimulation (TMS), is indicated as not
inducing auditory artefacts, and the voltage needed to hold the current constant decreases after a
LUCID DREAMING AND CONSCIOUSNESS 47
short time, becoming sub-threshold for evoking peripheral sensations that could otherwise
interfere, or even awaken, the participant (Noreika et al., 2010).
In Stumbrys and colleagues study (2013), the final sample was composed by nineteen
subjects (N = 19; 13 female and 6 male; age range: 21 to 33 years), recruited through e-mail
advertisements sent to psychology students and known lucid dreamers. The inclusion criteria
for this study were: one or more recalled dreams a week (measured on a 7-point scale), good
sleep, and no serious health problems. Later on, a fourth criterion was added in the form of an
eight-point scale, for the purpose of estimating the frequency of lucid dreaming. The dream
recall frequency median value reported was: several times a week; and the lucid dream
frequency median value reported was: about once a month (Stumbrys et al., 2013). Eleven
subjects were considered frequent lucid dreamers, as the authors took into account Snyder and
Gackenbach (1988) terminology (lucid dream ≥ once a month = frequent lucid dreamer). All
subjects were paid for their participation (the amount is not revealed), and gave written consent
(Stumbrys et al., 2013).
In this study, the procedure required for the participants to spend three consecutive
nights in the sleep laboratory with uninterrupted PSG recording (Stumbrys et al., 2013). The
first night was used for adaptation, screening for sleep disorders, and screening for sensitivity to
the tDCS. In that night, the PSG included EEG, EOG, submental and leg EMG,
electrocardiogram (ECG), and four respiration measures. For the other two subsequent nights,
the experimental ones, the PSG recordings included EEG, EOG, submental EMG, and ECG. In
these two experimental nights, subjects received tDCS stimulation in one, and sham stimulation
on another, in a randomized and counter-balanced order (Stumbrys et al., 2013). Two pairs of
conductive rubber electrodes, inside saline soaked sponges, were used to deliver the
stimulation. The anodes were applied to the DLPFC, and the cathodes were applied to the
supraclavicular area. The lucid dreaming signalling sequence consisted of L-R-L-R-L-R eye
LUCID DREAMING AND CONSCIOUSNESS 48
movements, and was to be repeated at a rate of once a minute, while lucidity lasted (Stumbrys
et al., 2013).
Furthermore, upon awakening, a detailed dream report was firstly elicited, seconded by
a self-evaluation of the intensity of positive and negative emotions during the dream, by means
of two four-point scales. Thirdly, participants were to answer two questionnaires verbally: the
Metacognitive, Affective, Cognitive Experience questionnaire (MACE; Kahan & LaBerge,
2011), which contains seven items, scored on a five-point scale, to assess different types of
meta-cognitive activities; and the Dream Lucidity Questionnaire (DLQ; Stumbrys et al., 2013),
which encloses twelve items, scored on a five-point scale, and was constructed for this
experiment by the authors, “to measure different aspects of lucidity within dreams” (Stumbrys
et al., 2013, p. 1216), evaluating different types of awareness, control and remembrance. The
dream reports were later on scored by an external judge, for lucidity and bizarreness. A three-
point scale was used to evaluate the lucidity of the dream, and dream bizarreness was assessed
by a four-point scale (Stumbrys et al., 2013).
The study conducted by Stumbrys and colleagues (2013) yielded a total of one hundred
and nine REM awakenings, but it would seem that the stimulation had disruptive effects in
REM sleep, leading to awakenings when tDCS was applied. Only one SVLD was recorded
during REM sleep, in a tDCS night, in which there were two signals, after three and four
minutes since the beginning of the tDCS stimulation (Stumbrys et al., 2013). In this particular
situation, the subject awakened by herself, after the second eye-signalling, during the third
REM period of the night. Early in the same night, the subject also signalled, but this time from
NREM N2 sleep, which is very intriguing indeed (Stumbrys et al., 2013).
According to the authors (Stumbrys et al., 2013), dream reports were significantly
longer, and rated as more lucid, on tDCS nights than on sham stimulation nights. Also, longer
dream reports were pointed to have more externally-focused meta-cognition. Relating judge
LUCID DREAMING AND CONSCIOUSNESS 49
scoring, seven dream reports were rated as having clear indications of lucidity, four from tDCS
nights, and three from sham nights (Stumbrys et al., 2013). The authors argue that, taking into
account the participants self-rating of dreams, the subjective experiences of dreaming were
affected by tDCS stimulation delivery over the DLPFC during REM sleep, resulting in
increased dream lucidity, thus confirming the initial hypothesis (Stumbrys et al., 2013). As such,
the authors conclude that the study provides preliminary empirical support for the causal
involvement of the DLPFC in lucid dreaming, at least on the neurophysiological level
(Stumbrys et al., 2013).
Notwithstanding, the authors also refer that tDCS stimulation effects were not very
strong, and a post-hoc analysis shown pronounced effects only in frequent lucid dreamers
(Stumbrys et al., 2013). It is interesting to point out, however, that these subjects reported
increased awareness that their physical body was asleep, increased awareness that the dream
objects and characters were not real, and also an overall lucidity (Stumbrys et al., 2013).
However, it would seem that infrequent and non-lucid dreamers did not report effects of
increased lucidity, in tDCS stimulation nights (Stumbrys et al., 2013). The authors have done a
very good analysis on the reasons for this, pointing out several aspects, from which it may be
interesting to mention the possibility that activation of a wider network of different brain areas
may be needed to achieve lucidity in dreams (Stumbrys et al., 2013), as in the frontoparietal
control system mentioned earlier. Other possibility lies in that tDCS may have stimulated other
areas besides DLPFC (Stumbrys et al., 2013). In any way, the authors conclude that tDCS might
not be a promising tool for lucid dream induction on a practical level (Stumbrys et al., 2013).
Another relevant study, from Voss and colleagues (Voss, Schermelleh-Engel, Windt,
Frenzel, & Hobson, 2013), set out to develop the Lucidity and Consciousness in Dreams
(LuCiD) scale, in an attempt to better assess the major and minor determinants of dream
lucidity, through the comparison between lucid and non-lucid dreams from REM sleep.
LUCID DREAMING AND CONSCIOUSNESS 50
According to the authors, the LuCiD scale is said to be based in theoretical considerations and
empirical observations, analysed and validated through factor-analysis. The authors also claim
that this scale was the first empirically-based approach to measure and define consciousness in
different types of dreams, and its item construction was aimed at identifying differences
between higher and lower levels of consciousness in dreams (Voss & Hobson, 2015; Voss et al.,
2013).
The final version of this scale includes twenty-eight items or statements (please refer to
Appendix B for a full view of LuCiD scale final version), each followed by a six-point scale (0
= strongly disagree to 6 = strongly agree). According to the factor analysis performed by the
authors, non-lucid and lucid dream consciousness is said to be describable using the following
eight elements (Voss & Hobson, 2015; Voss et al., 2013; Voss & Voss, 2014):
1. Insight – lucid insight into the fact that what one is currently experiencing is not real,
but is only a dream (scale items: 1, 3, 8, 9, 16, 19).
2. Control – rule over thought and actions in dreams, as in volition but also as in control of
dream plot (scale items: 4, 6, 10, 14, 23).
3. Thought – about other dream characters (scale items: 5, 12, 22).
4. Realism – a sense of perceptual realism related to the similarity between emotions,
thoughts, and events in lucid dreaming and wakefulness, judged after awakening from
the dream (scale items: 7, 17, 20).
5. Memory - access to elements of waking life memory in the dream (scale items: 2, 13,
18, 24).
6. Dissociation – similar to taking a third person perspective (scale items: 11, 15, 21).
7. Negative emotion (scale items: 26, 28).
8. Positive emotion (scale items: 25, 27).
According to the authors (Voss et al., 2013), the scale was constructed through three
LUCID DREAMING AND CONSCIOUSNESS 51
main steps: firstly, fifty theory-based items were tested in a first survey; secondly, from those
fifty items, twenty-four were selected through factor-analysis as suited to distinguish between
lucid and non-lucid dreams, plus four new items on emotion were added; thirdly, a new
confirmatory factor analysis was done, combined with a data assessment for extensive scale
validation (Voss et al., 2013). For this purpose, two surveys were done, advertised among
students at Bonn University (Germany), and also to participants of a lucid dream group of the
same University. On the first survey, relating to the first step, one-hundred and fifty-eight dream
reports were used, mainly from paper and pencil questionnaires, but also from online. These
questionnaires were answered by one-hundred and forty-nine participants (N = 149; 118
females and 31 males; mean age = 24,4 ± 0,7 years). Fifty of these dream reports were
reportedly lucid, and one-hundred and eight non-lucid (Voss et al., 2013), but the authors do not
specify how this assessment was made. The procedure relied on asking for a recent single
dream report, and afterwards answer all questions relating to the dream.
The second survey was done with the final version of the LuCiD scale, for validation
purposes. In this survey, one-hundred and fifty-one dream reports were elicited (117 from
laboratory setting and 34 from paper and pencil answers). It would seem that eighty of these
reports come from females, and seventy-one from males. (Voss et al., 2013). The authors do not
state clearly how many participants this second survey had, which is rather confusing. Also, the
authors do not specify how many of the one-hundred and fifty-one dreams from the second
survey were lucid or non-lucid, as it had been done for the first survey. According to Voss and
colleagues (2013), the procedure for the dream reports from paper and pencil was the same as in
the first survey. For the dream reports in the laboratory setting, awakenings from REM sleep
were done. Subjects arrived at 9 p.m. and were instrumented for regular PSG. Afterwards, the
LuCiD scale items were read out by an experimenter, and time was allowed for full
comprehension. REM sleep awakenings started at 3 p.m., and were made after five minutes of
LUCID DREAMING AND CONSCIOUSNESS 52
monitored REM sleep. After the dream report, an experimenter read out the questionnaire items,
and marked the answers. Each subject spent up to three non-consecutive nights at the
laboratory, gave informed consent, and received a fifty Euro (€50,00) compensation for each
night (Voss et al., 2013).
In accordance to Voss and colleagues (2013), this study indicates that three of the LuCiD
scale elements are substantially increased in lucid dreaming: insight into the fact that one is
currently dreaming (Insight), control over the dream plot (Control), and dissociation similar to
taking a third-person perspective (Dissociation). Figure 1 (below) shows the mean scores for
non-lucid and lucid dreams, in the eight elements of the LuCiD scale (Voss et al., 2013). One
can only have an approximated idea of the mean scores, since the authors do not provide the
exact numbers in the text of the study.
In close relation to the previously analysed study, Voss and colleagues (2014) attempted
to discern if lucid dreaming is dependent of the presence of gamma activity, as a necessary
condition, or if it can be elicited by other causal ways, such as stimulation with other
frequencies, as a causal enabling condition. In a simpler manner: if gamma activity triggers
LUCID DREAMING AND CONSCIOUSNESS 53
lucid dreaming or if lucid dreaming triggers gamma activity. The authors used trans-cranial
alternating current stimulation (tACS), which is said to produce no acoustic noise and no tactile
sensations, to stimulate the fronto-temporal region of the human brain, at various frequencies.
In this study, conducted by Voss and colleagues (2014), twenty-seven healthy volunteers
(N = 27, 15 female and 12 male, age range: 18 to 26 years), inexperienced in lucid dreaming,
screened for psychiatric and sleep disorders, and free of central nervous system acting
medication, were selected as participants. Up to four nights were spent by the subjects at the
sleep laboratory of the Department of Clinical Neurophysiology, at the University Medical
Centre Göttingen (Germany). Throughout all nights, PSG recordings were done with EEG (22
channels), EOG, and submental EMG. The procedure for this experiment was as follows: the
subjects were let to sleep up until 3 a.m. and, from that moment on, tACS was fronto-
temporally applied for thirty seconds, if a period between two to three minutes of uninterrupted,
arousal-free REM sleep occurred. This would happen at a frequency of either 2, 6, 12, 25, 40,
70 or 100 Hz (stabilized at better than ±0,01 Hz) or sham. To avoid order effects, the applied
stimulation frequencies were counterbalanced across subjects and across nights (1-4).
Participants were awakened five to ten seconds after stimulation, and were asked to provide a
full dream report, and afterwards to rate the twenty-eight items of the LuCiD scale. The scale
items were read to subjects by the experimenters.
Voss and colleagues (2014) report that the EEG underwent quantitative analysis for all
stimulation conditions and sham, and REM-like sleep persisted throughout the procedure
phases, up until awakening, documented by unchanged REMs and muscle atonia (PSG). It
would seem that activity in the lower gamma frequency band increased during stimulation with
40 Hz (mean increase between 37-43 Hz = 28%), and also during stimulation with 25 Hz (mean
increase between 22-28 Hz = 12%), although in a lesser degree. Apparently, stimulation in
lower (2, 6, 12 Hz) or higher frequencies (70 or 100 Hz), or sham, did not produce an activity
LUCID DREAMING AND CONSCIOUSNESS 54
increase. This lead the authors to speculate that REM sleep was altered through the stimulation
(40 Hz and 25 Hz frequencies), producing a state change similar to the state of lucid dreaming.
The authors also argue that, if one takes into account the subjective ratings of lucidity,
lucid dreams were most prominent during stimulation with 25 Hz (58%) and with 40 Hz (77%).
Moreover, it is also argued that increases in 40 Hz band activity at fronto-temporal sites
correlate significantly with mean scores on the factors Insight and Dissociation, of the LuCiD
scale (Voss et al., 2014; please refer to Figure 2 below). There seems to be a problem here,
because if one compares the mean score for the element Insight of the LuCiD scale in the
previous study (Insight mean score = ~ 3,3; Voss et al., 2013; please refer to Figure 1), with the
mean score for the same element in this study (Insight mean score = ~ 0,6; Voss et al., 2014;
please refer to Figure 2), there is clearly a difference in the criterion used in both studies.
To sum up, Voss and colleagues (2014) propose that current stimulation in the lower
LUCID DREAMING AND CONSCIOUSNESS 55
gamma band during REM sleep has an influence in ongoing brain activity, inducing meta-
awareness in dreams. Lucid dream state consciousness seems to be related to synchronous
oscillations around 25 and 40 Hz, suggesting that lower gamma-band activity correlates with
elevated meta-awareness. According to the authors, these results may provide the first causal
evidence of frequency-specific cortical oscillations in humans induced by tACS, also appearing
to demonstrate altered conscious awareness as a direct consequence of induced gamma-band
oscillations during sleep (Voss et al., 2014). It would seem that stimulating the brain in the
gamma frequency range, which is also the frequency band most often associated with conscious
awareness in the awake state, facilitates the ability to engage in lucid dreaming during REM
sleep (Payne, 2014).
Voss and colleagues (2014) experiment is pointed out in the literature (Payne, 2014) as
another major breakthrough in lucid dream and consciousness research, and has the backing of
none other than Nature Neuroscience journal. Nonetheless, the eliciting of lucid dreams is done
through the LuCiD scale, with a different criterion, and are not SVLDs. This may be a problem,
as the experimenters rely only on a subjective report, which is then rated on the LuCiD scale
with a different criterion than the one used when validating the scale, without having it
physiologically verified. These may be very interesting preliminary results indeed, but these
results are also in want of replication, probably with the inclusion of SVLDs. Lower gamma
band stimulation of the fronto-temporal region of the human brain may enhance neuronal
synchronization and set the stage for lucidity in dreams, but the main actor is still needed.
Along the same vein, Dresler and colleagues (2014a) studied different aspects of
volition during non-lucid dreaming, lucid dreaming, and wakefulness, through the use of an
adapted version of the Volitional Components Questionnaire (VCQ) in lucid dreamers. The
authors hypothesized that experienced volition would be generally higher in both wakefulness
and lucid dreaming compared to non-lucid dreaming. For this study, ten healthy subjects (N =
LUCID DREAMING AND CONSCIOUSNESS 56
10; 5 female and 5 male; age range: 19 to 47 years) were recruited at the University of Munich
(Germany), or from a database of volunteers of the Max Planck Institute of Psychiatry, also in
Munich. All subjects were said to be experienced lucid dreamers (reported mean frequency =
1,9 ± 0,7 lucid dreams per week), and the authors verified lucid dreaming ability by SVLDs in a
sleep laboratory with PSG recordings for five subjects, and assessed by self-report on the other
five subjects (Dresler et al., 2014a).
For measuring volition in different states of consciousness, the authors adapted the
German short version of the VCQ (SelbststeuerungsInventar, SSI-K3; Dresler et al., 2014a).
The VCQ is an instrument that measures different aspects of volitional competence, with the
purpose of assessing the subjective experience of volitional components supporting central
coordination of goal-maintenance and self-maintenance (Kuhl and Fuhrmann, 1998; Dresler et
al., 2014a). The short version of the VCQ includes thirteen sub-scales with four items each, and
subjects are asked to rate the extent to which the item applies to themselves on a four-point
scale (1 = not at all to 4 = wholly). From the thirteen sub-scales of the short version, the authors
chose to use six: self-determination, planning ability, intention enactment, powers of
concentration, self-access, and integration. An overall score consisting of the mean of all six
sub-scales was calculated by the authors, as a measure for the general experience of volitional
capacity (Dresler et al., 2014a).
The procedure for this experiment (Dresler et al., 2014a) consisted on the completion of
the questionnaire at least once for the three states of consciousness: in the morning after
awakening from a non-lucid dream, in the morning after awakening from a lucid dream, and
before going to bed in the evening, after a normal day of wakefulness. This was to be done by
the subject through the rating of the general experience during the respective state, using the
preceding dream or day as a reminder thereof. Non-lucid dreaming state yielded twenty
questionnaires from five different subjects (5s → 20q), lucid dreaming state yielded fourteen
LUCID DREAMING AND CONSCIOUSNESS 57
questionnaires from four different subjects (4s → 14q), and wakefulness state yielded fifteen
questionnaires from four different subjects (4s → 15q). For those participants who completed
the questionnaire more than once for one of the three states of consciousness, the authors used
the mean score of the given state for further analysis (Dresler et al., 2014a).
Dresler and colleagues (2014a) report that, after inferential statistical analysis of the
VCQ overall score, volition was strongly experienced by the participants during wakefulness
and lucid dreaming, but considerably less so during non-lucid dreaming. The analysis of the six
sub-scales is reported to reveal a significantly more pronounced self-determination during both
wakefulness and lucid dreaming states, than in non-lucid dreaming state. This sub-scale is
pointed to be the most prototypical volitional component, and inquires to what degree the
subject experiences the ability to act freely according to his will (Dresler et al., 2014a). This
results seems to be in line with the overall score, thus the authors point out this confirms the
study hypothesis that volition is more marked during both wakefulness and lucid dreaming
states, than in non-lucid dreaming state (Dresler et al., 2014a).
This would seem a very interesting study, not for the fact that subjects are reporting their
consciousness states outside a sleep laboratory, which in itself has its strengths and weaknesses.
For once, the subject is in his own natural environment, not surrounded by machinery and
plugged with equipment, thus going through the states in a natural way. On the other hand, the
questionnaires were completed in the morning, in the non-lucid and lucid dreaming state cases,
which may have biased the reports, since the awakening may not have happened immediately
after the occurrence of the dream. Nevertheless, the authors point out this and some other
limitations in the study (Dresler et al., 2014a), and this may be taken as preliminary evidence
for the similarity of the volitional component marked presence, in the wakefulness and lucid
dreaming states.
One of the most recent studies, conducted by Filevich and colleagues (2015), procured
LUCID DREAMING AND CONSCIOUSNESS 58
relationships between the neural correlates of lucid dreaming and meta-cognition. In particular,
if pre-frontal gray matter volume positively associated with experienced dream lucidity, and if
brain areas associated with high lucidity showed increased blood oxygen level-dependent
(BOLD) activity during meta-cognitive monitoring. The authors report that the sample
consisted on sixty-nine healthy participants (N = 69; 34 female and 35 male; age range: 18-37
years), recruited from a database by telephone contact. In this recruiting contact there was no
mention of lucid dreaming. From the initial sample, sixty-three participants were included in the
final analyses. None of them had had history of psychiatric illness in the previous tear, and were
all right-handed (Filevich et al., 2015).
The procedure for this experiment, conducted by Filevich and colleagues (2015),
consisted on two phases. In the first phase, to assess their meta-cognitive monitoring, subjects
went through a thought-monitoring task, with two eleven minute runs, concomitant with MRI
scanning. Afterwards, subjects were apprised about lucid dreams, and received a link to an
online questionnaire. For the second phase, to assess their in-dream lucidity in the week
immediately after the scanning, the participants were instructed to complete the online survey
once every morning, recalling their most recent and most lucid dream from the previous night.
The survey included the following components: one question to determine dream recall
frequency (6-point scale), one question about the frequency of lucid dreams (8-point scale;
Schredl & Erlacher, 2004), the LuCiD scale (Voss et al., 2013), computed as the simple sum of
all items, and subtracted from the elements Negative Emotion and Realism, a rumination and
self-reflection questionnaire, two questionnaires on public and private self-consciousness, and a
visual imagery scale (Filevich et al., 2015).
The authors (Filevich et al., 2015) analyses were based on a combination of the LuCiD
scale and frequency scores, established on the assumption that this composite score would
assess both quality and quantity of lucid dream capability, and denominated the resulting
LUCID DREAMING AND CONSCIOUSNESS 59
measure trait-lucidity. Subjects were then median split into two groups (N = 31 for each group),
high and low lucidity, according to score. A brain structure comparison, using voxel-based
morphometry (VBM), was then made. Participants placed in the high-lucidity group exhibited
greater grey matter volume in the frontopolar cortex, Brodmann's area (BA) 9/10, when
compared with those in the low-lucidity group. In addition, during thought monitoring, the BA
9/10 regions identified through structural analyses revealed increases in BOLD signal in both
groups, but more strongly in the high-lucidity group. The authors (Filevich et al., 2015) claim
that the results reveal shared neural systems between lucid dreaming and meta-cognitive
function, particularly in thought monitoring. Moreover, the results seem to suggest BA 10 as a
candidate mediator of meta-cognition, and lucid dreaming a specific form of meta-cognition
that uses the same neural mechanisms as thought monitoring.
Several authors (Filevich et al., 2015; Hobson & Voss, 2011; Kahan & LaBerge, 1994)
suggest that, during REM sleep, deactivations of the DLPFC and frontopolar cortex underlie
decreases in meta-cognitive monitoring, whereas in lucid dreaming, subjects regain reflective
capabilities and become meta-cognitively aware of their current state of consciousness. Direct
relationship between the neural basis of lucid dreaming and meta-cognition is often assumed,
but had not been tested yet (Noreika et al., 2010). Specifically, the connection between meta-
cognitive processes in lucid dreaming, and meta-cognitive variability during wakefulness, in
what concerns inter-individual variability in frontopolar cortex neuroanatomy (Filevich et al.,
2015).
In summary, the line of research presented here is a mere fraction of the experiments on
lucid dreaming done until now. These specific studies relate directly to the use of lucid
dreaming for obtaining a deeper knowledge of the neural processes pertaining consciousness as
a state. The overall results seem to point out lucid dreaming as a way to research mind-body
interactions (Erlacher et al., 2003, 2014), and may even considered it a new state of
LUCID DREAMING AND CONSCIOUSNESS 60
consciousness, with features of REM sleep and wakefulness (Voss, et al., 2009). A possibility of
correlation with brain maturation is suggested (Voss et al., 2012), and an association with meta-
awareness and meta-cognition appears to be strengthened (Dresler et al., 2012, 2014a; Filevich
et al., 2015; Hobson & Voss, 2011; Voss et al., 2013). Furthermore, it may be possible to induce
meta-awareness, or insight into the fact that one is dreaming, during REM sleep (Voss et al.,
2014), although this last suggestion is in urgent need of a replication.
In the next section, the approaches and connections between lucid dreaming and
consciousness are examined, and also the theoretical foundations and inter-relations between
them.
LUCID DREAMING AND CONSCIOUSNESS 61
Part IV - Lucid dreaming and consciousness
1. Bridges between lucid dreaming and consciousness
One can say that consciousness, as initially defined in this investigation (please refer to
Part I, sub-section 1), may be considered state dependent, taking into account how it is reported
to undergo alterations in parallel with sleep changes in the brain. Therefore, one can also say
that consciousness seems to change its intensity and character as the brain changes state during
the sleep-wake cycle. As such, it would now seem clear that the kind of consciousness one
experiences is a function of the state of the brain (Hobson, 2005).
With this said, one approach to scientifically study consciousness may rely on tracking
changes in the brain and changes in the mind simultaneously, and afterwards to map back and
forth between the two domains (Hobson, 2005). This may be done with the use of first-person
data, as it is very difficult to study subjectivity without it, and consciousness is a subjective
state. Scientific laboratory studies of human consciousness using lucid dreams seem to be a
straightforward way to do this, as long as laboratory lucid dreaming is rigorously defined as
phasic REM sleep, and temporal dream recollections consistent with eye movement signals are
counted for analysis (Brylowski, 2010), so as to produce SVLDs.
In Hobson's (2009a) opinion, lucid dreaming is a state of consciousness in the middle of
waking and non-lucid dreaming, and there is empirical evidence for it, pointing out Wehrle and
colleagues (2007) and Voss and colleagues (2009) studies. As mentioned before (Part II, sub-
section 1, and Part III, sub-section 2 respectively), the former study gives preliminary evidence
for a thalamocortical network specific for phasic REM periods (Wehrle et al., 2007), and the
later study provides preliminary evidence that lucid dreaming appears to have EEG power and
coherence profiles that are significantly different from non-lucid dreaming (Voss et al., 2009).
With the measurement of the temporal correlation between frontal and occipital EEG patterns, it
LUCID DREAMING AND CONSCIOUSNESS 62
would seem that subjects have more EEG coherence when lucid than when not, being the EEG
coherence considered the degree to which the brain waves are synchronized across regions
(Hobson, 2009b; Voss et al., 2009).
Therefore, lucid dreaming is posited to present itself with more 40 Hz power than non-
lucid dreaming, especially in frontal regions, which are thought to associate with working
memory, self-awareness and volition, the characteristics that are normally absent in non-lucid
dreaming, and seem to be needed for a dream to become lucid (Voss et al., 2009). This kind of
high-frequency EEG activity, both 40 Hz power and fronto-occipital coherence, may represent
the synchronization of cortical neuronal activity that is pointed out to be necessary to effect the
temporal binding believed to be essential to waking consciousness (Hobson, 2009a, 2009b;
Singer, 2001).
The finding of a correlation between the three conscious states - REM dream, lucid
dream, and waking - and 40 Hz power seems to suggest that 40 Hz may be a substrate of
consciousness (Singer, 2014). Cognitive contents need to be selected by attentional mechanisms
to be consciously processed during wakefulness, and attentional selection is said to happen
through the synchronization of neuronal responses in the gamma frequency range (Fries,
Reynolds, Rorie, & Desimone, 2001; Lima, Singer, & Neuenschwander, 2011).
Taking into account the notion of lucid dreaming as an indication that waking and
dreaming can coexist, it would seem that different regions of the same brain underlie waking
and dreaming. When subjects become lucid they appear to increase their self-awareness as the
40 Hz power of the frontal EEG increases (Voss et al., 2009), and this seems to connect with
Singer (2014) hypothesis that waking consciousness results from high frequency
synchronization of the forebrain. Accordingly, dream lucidity could be a by-product of
increased 40 Hz activation in REM sleep (Hobson, 2014).
Notwithstanding, Hobson (2009a) also points out lucid dreaming as an example of
LUCID DREAMING AND CONSCIOUSNESS 63
dissociation, but there appear to be conceptual problems with this, as the author asks: how can
the brain be in two different states at once? (Hobson, 2009a) But is this so? Or can one rather
say that there is a continuum instead of defined static states? Nevertheless, state dissociations
are quite a commonplace, as proven by parasomnias, such as sleep-walking, a NREM
parasomnia, where the gait-generator and navigational system of the brain stem may be in full
operation while the cerebral cortex is in NREM sleep stage IV, or as sleep paralysis, a REM
parasomnia, where the dreamer wakes up from REM and is unable to move due to persistent
REM sleep motor inhibition (Mahowald, 2009; Mahowald & Schenck, 2005). These and other
identified dissociations are pointed to be strong evidence that there is more than one state
present in several occasions, like a cross-state fluidity (Hobson 2009a).
On the other hand, Brylowski (2010) disagrees on Hobson's (2009a) referencing lucid
dreaming as a dissociation, stating that this is not helpful and not empirically supported because
there seems to be no consensus on the concept of dissociation, neither in psychiatry nor in
neurosciences, and it has not been proven that lucid dreaming is a pathological state.
Alternatively, the three conscious states of waking, non-lucid dreaming, and lucid dreaming
may instead be part of a unique continuum, and not psychologically distinct, except for
experimental purposes, in which they should be defined as physiologically distinct (Brylowski,
2010). In the same line, Holzinger (2010) mentions that lucid dreams can be viewed as
paradoxical dreams, where paradoxical relates to the concept of adding secondary process
thinking to primary process thinking, which causes a new state to emerge that is deeper than
non-lucid dreaming. As such, lucid dreaming could be described as an associative state, instead
of a dissociative one.
Earlier on, LaBerge and DeGracia (2000) had proposed that consciousness may be
present in all dreams and may also be measurable on a continuum, in which one oscillates
between the two poles of ”lucidity” and ”non-lucidity”. The authors based this assumption on
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the concept that individual variation seems to characterize the experience of lucid dreaming, as
it is composed by a flow of subjective events brought forth by brain processes, like all forms of
conscious experience (LaBerge & DeGracia, 2000). It would seem that two factors have a
strong presence in this equation: firstly, the belief systems and learning of the dreamer, that
seem to shape the lucid dream experiences, secondly, the factors that seem independent of the
belief systems and learning of the dreamer.
By the same token, already in 2000 LaBerge and DeGracia attempted to connect lucid
dreaming research with consciousness research, which clearly clashed with Crick and Koch's
1998 article: “Consciousness and Neuroscience”. In this particular article, lucid dreaming was
said to be a state with no special features that made it experimentally advantageous for
neuroscience study of consciousness (Crick & Koch, 1998). Nevertheless, LaBerge and
DeGracia (2000) suggested using the framework of the global workspace model of
consciousness developed by Bernard Baars (1988) for a systematic comparison between waking
state, lucid, and non-lucid dreaming. It was then hypothesized that waking state consciousness
is maintained by a context hierarchy of unconscious elements that initially requires conscious
participation to be formed, but afterwards frames conscious experience.
According to the authors (LaBerge & DeGracia, 2000), in non-lucid dreams, the
dreamer consciousness seems also constrained by unconscious contextual elements during the
dream, although the conceptual situation may be little related with episodic experiences of
waking, even though there seems to be memory transfer from waking to dreaming, but very
little in reverse. In both cases, it is proposed by LaBerge and DeGracia (2000) that the dreamer
assumes he is awake, not questioning the events that surround the experiences. However, in
lucid dreams the dreamer appears to able to recall details of his waking life within the
experience, and vice-versa, in waking state the lucid dreamer remembers the details of the
dreams, seemingly contributing to the episodic memory of the waking personality. Likewise,
LUCID DREAMING AND CONSCIOUSNESS 65
there seems to be a continuity of consciously accessible memory that links lucid dreams and
waking experience, as in a two-way memory transfer (LaBerge & DeGracia, 2000).
Lastly, LaBerge and DeGracia (2000) had distinguished lucid and non-lucid dreams by
the contextual structure that underlies dream consciousness, that is, non-lucid dreams can be
characterized by the formation of global contexts that vary from dream to dream, whereas lucid
dreams are characterized by a distinct and durable context, the lucid dream context. Lucidity in
dreaming is pointed out to be the sum of meta-cognition plus the conscious access of memories
from the waking experience.
Contemporaneously, cognitive neuroscience experiments on lucid dreaming seemingly
follow a line of research concomitant with a divide between primary and higher-order or
secondary aspects of consciousness (meta-awareness, abstract thinking, volition, and meta-
cognition; primary and secondary consciousness are further detailed in the next sub-section). A
parallel may be made between this divide and the concepts of phenomenal and reflective
consciousness. Likewise, Dresler and colleagues (2014a) suggest that neuroimaging research
into the neural correlates of lucid dreaming, and its association with meta-cognitive and
volitional processes, may support the notion of this phenomenon as a promising approach for
the investigation of higher-order aspects of consciousness.
Moreover, there seems to be a remarkable overlap between the neural correlates of lucid
dreaming, and areas and networks that serve meta-cognitive and volitional capabilities (Brass,
Lynn, Demanet, & Rigoni, 2013; Roskies, 2010), which are pointed to be the same areas that
show the strongest differences between human and non-human primates (Dijksterhuis & Aarts,
2010; Frith, 2013), helping to build the suggestion that higher-order aspects of consciousness
are most pronounced in humans (Dresler et al., 2014a). In research, the use of combined
neuroimaging methods and refined measures of the degree of lucidity, such as scales that assess
several dimensions of volition and meta-cognition (Kahan & Sullivan, 2012; Voss et al., 2013),
LUCID DREAMING AND CONSCIOUSNESS 66
may help disentangle the specific involvement of brain regions in higher-order aspects of
consciousness, adding up to the understanding of the neural correlates that underlie the multiple
facets of human consciousness (Dresler et al., 2014a).
For the sake of argument, if one can have meta-cognition in waking state, but not in
dreaming state, and if there is a lucid dreaming state where one can have meta-cognition and
still be dreaming, then this state would be highly informative for researching higher-order
aspects of consciousness. More so, in Spoormaker and colleagues (2010) opinion, if one
contrasts lucid and non-lucid dreaming, especially to unveil the brain regions whose activity
and functional connectivity are crucial for consciousness. In fact, to Spoormaker and colleagues
(2010), non-lucid and lucid dreaming may be the contrast between primary and secondary or
higher-order consciousness, and lucid dreaming may be critical to the full understanding of the
neural correlates of higher-order consciousness, taking into account that lucid REM sleep is still
REM sleep according to the AASM criteria (Iber et al., 2007). Taking this into account, lucid
dreaming is suggested to provide the only case known where primary consciousness as
experienced in dreams can contrast with secondary consciousness in the same state
(Spoormaker et al., 2010).
In the next sub-section, the concepts of protoconsciousness, primary consciousness, and
secondary consciousness will be further reviewed, in what concerns the contemporary
connections between lucid dreaming research and consciousness research.
2. The protoconsciousness and primary-secondary consciousness hypotheses
The protoconsciousness theory is based on the findings that newborn mammals show
high amounts of REM sleep (Hobson & Schredl, 2011), and attempts to answer the question of
what is the function of dreaming as a subjective experience during sleep (Hobson, 2009b). It
suggests that the development and maintenance of waking consciousness and other higher-order
LUCID DREAMING AND CONSCIOUSNESS 67
brain functions depend on brain activity during sleep (Hobson & Schredl, 2011). In short, what
is meant by Hobson (as cited in Revonsuo, 2015) with protoconsciousness is a state that is prior,
and causally essential, to the development of consciousness: I REM, therefore I will be.
Hobson (2009b) contemplates a human brain that has an auto-creative nature, in respect
to image creation and fiction producing. Protoconsciousness theory proposes that, before the
emergence of language and consciousness as one knows it, the brain gets ready to be conscious
by being auto-creative, translating the genetic paradigm into a functional program, by following
the directions of the external world and the directions of its own internal programs (Hobson,
2009b). This means that when humans are born they already possess a brain protoconscious, in
the sense that is ready to be conscious (Vogelsong, 2013).
In a published conversation with Vogelsong (2013), Allan Hobson presents his
reasoning: the mind is an aspect of the body yet to be understood clearly, in what the mind is the
subjective part and the body the objective one, not in a dualistic way, but in a dual aspect
monism. It would seem that the subjective part cannot operate without the objective part, though
the objective part can still exist, even if the subjective part is long absent or altered. Hobson
goes on, pointing out that dualism is very attractive because the mind-brain relation feels like a
dualistic system, in the sense that when one thinks, one does not have any awareness of thinking
as a brain function, as the brain behaving in a certain way. In like manner, Hobson refers that
monism is a very difficult state to achieve, because the subjective experience is very isolated
from the objective part.
Hobson (Vogelsong, 2013) carries on stating that, when dreaming, humans are
confronted with the fact that the brain has changed state, and the way to understand the change
of states in the brain is by comparing the dream experience with the waking experience. The
dual aspect monism is posited to reinstate the first-person subjective accounts into a more
complete science. Moreover, Hobson (Vogelsong, 2013) points out lucid dreaming as a very
LUCID DREAMING AND CONSCIOUSNESS 68
important evidence that something like the protoconsciousness hypothesis may be correct,
because in lucid dreaming there is primary consciousness, meaning awareness of self, space,
movement, emotion, that are typically present in non-lucid dreaming, but something else has
been added, in this case a self that observes and changes the dream.
Primary consciousness can be defined as simple awareness that includes perception and
emotion, which is ascribed to most mammals (Hobson, 2009b). Secondary consciousness
depends on language, and includes the following features: meta-awareness, abstract thinking,
volition, and meta-cognition (Edelman, 1992). In adult humans, REM sleep non-lucid dreams
are suggested to have features of primary consciousness, mainly perceptions and emotions, but
lack characteristics of secondary consciousness (Hobson, 2009b).
Intensity and quality of consciousness seem to vary during the sleep-wake cycle in
humans, and whether one is awake and alert with all the secondary aspects of consciousness,
asleep with very diminished awareness, or dreaming with the internally generated perceptions
and emotions of primary consciousness, depends on three physiologically identifiable states of
the brain: waking, NREM sleep, and REM sleep (Hobson, 2009b).
REM sleep non-lucid dreams seem to be implicated only with the immediate present,
with an uncontrolled access to the past or anticipated future (Edelman, 2003; Hobson & Voss,
2011; Voss et al., 2009), and seem to have an abundance in features of primary consciousness,
especially perceptions and emotions, organized in a scenario-like environment (Edelman, 2003;
Hobson, 2009b). These characteristics are used as a rationale to assume non-lucid dreams as a
primary state of consciousness (Hobson, 2009b; Hobson & Voss, 2010, 2011; Voss et al., 2014).
In this primary state, humans usually consider to be awake, not knowing that are dreaming, thus
not recognizing its own true condition, its incoherence, its limitation of thought and its
impoverishment of memory (Hobson, 2009b; Hobson & Voss, 2011; Voss et al., 2009).
Furthermore, it would seem that primary consciousness co-develops with REM sleep and the
LUCID DREAMING AND CONSCIOUSNESS 69
latter is a virtual reality generator for the brain and, when active, dream happens (Hobson &
Voss, 2010).
When awake, humans are said to enter a secondary mode of consciousness, which
includes higher order cognitive functions (Edelman, 2003; Hobson, 2009b; Hobson & Voss,
2010, 2011; Voss et al., 2009), thus waking consciousness can be defined as the awareness of
the external world, our bodies and our selves, as in meta-awareness (Edelman, 2003; Hobson,
2009b). In lucid dreaming, elements of secondary consciousness are said to coexist with
primary consciousness (Hobson, 2009a; Hobson & Voss, 2010; Voss et al., 2009, 2014), and this
coexistence is suggested to enable the dreamer to become aware of the fact that he is dreaming
while the dream continues (Hobson, 2009a, 2009b; Voss et al., 2009, 2014).
According to Hobson (2009b), REM sleep is pointed to be a recent behaviour in
evolutionary terms, regulated by the pontine brainstem, a phylogenetically ancient brain
structure, and an example how relatively new physiological functions can depend on old brain
regions. Although evolving separately in mammals and birds, there appears to be an early life
preponderance of REM sleep in both. Edelman (2003), Hobson and Voss (2010) suggest that the
primary consciousness system is activated in REM sleep in all animals that possess its
advantages, but as the brain continued to evolve, and elaborated its thalamocortical circuitry, it
became possible for animals to add secondary aspects of consciousness to their waking
repertory.
Around the twelfth week of human gestation, the volume of REM sleep is said to peak,
subsequently declining after birth, while at the same time cognitive capabilities and waking
time increase. Additionally, primary consciousness seems to decline and secondary
consciousness seems to grow in parallel with the development of the brain and the capacity for
prolonged waking (Hobson, 2009b).
Hobson and Voss (2010) suggest reflective consciousness as the phenomenon that
LUCID DREAMING AND CONSCIOUSNESS 70
distinguishes humans and primates from other animals, providing them a secondary form of
consciousness, which seems to be prerequisite for abstract thought and volition. Therefore, the
authors (Hobson & Voss, 2010) point out that consciousness may be at least bimodal, although
it may even be multi-modal, and research on sleep and dreaming has documented the state-
dependency of this bi-modality, that is expressed in the dreaming and waking brain physiology
and phenomenology.
Hobson and Voss (2011) also refer that only higher order animals, which possess the
capability of secondary consciousness, may suffer from psychosis. This leads them to conclude
that humans, and only humans, evince fully developed secondary consciousness, and so only
humans have minds that can become dysfunctional in ways that can be called psychotic.
The study of lucid dreaming may present consciousness research with a unique
opportunity to understand the mechanism of primary and secondary consciousness, and explore
the functional significance of their interaction (Hobson & Voss, 2010). Actually, the brain may
never be in one and only one state, and in fact dissociations abound, meaning that the brain can
be in several states at once, or probably fluctuate in a continuum of states that are pervasive,
and share elements of two or more states (Mahowald, 2009; Hobson & Voss, 2010).
Hobson (2009a) argues that lucid dreaming provides a model for the emergence of
Edelman's (2003) secondary consciousness, and its isolation in studies of lucid dreaming will
enable a revolutionary turn in neuroscientific studies of consciousness. Yet, according to
Kuiken:
”In his adaptation of this theoretical framework, Hobson circumvents Edelman's
proposal that language distinctively shapes secondary consciousness, instead, he
acknowledges that linguistic competence is manifest in both lucid and non-lucid
dreaming – and, by implication, in both primary and secondary consciousness.”
(Kuiken, 2010, p. 22)
LUCID DREAMING AND CONSCIOUSNESS 71
Kuiken (2010) continues his critic by also pointing out that it is unclear which neural
networks support the self of primary consciousness, as if there was no specific neural substrate
for the self of non-lucid dreaming. Lastly, the author also mentions that some aspects of meta-
awareness and volition, supposedly characteristic of secondary consciousness, can occur
independently of it.
In summary, the primary and secondary consciousness hypothesis brings the theoretical
support and endorsement to several experiments with lucid dreaming. Non-lucid dreaming is
stated as dominated by primary consciousness features, and the waking state by secondary
consciousness. Primary consciousness is advanced by Hobson and Voss (2010) to be the
necessary cognitive base on which secondary consciousness is built. The lucid dreaming
phenomenon brings about an excellent opportunity to monitor the resurgence of volition, meta-
awareness, and meta-cognition, inside REM sleep, which is usually dominated by perception
and emotion. This hypothesis also appears to give support to the idea of consciousness as a
flutuating phenomenon, in which the brain may produce at least two, or maybe several states
simultaneously. Actually, some avenues of research are opened by this hypothesis, such as to
discern if some primates and some birds do have secondary consciousness, and to what degree.
In the next sub-section, the primary-secondary dynamic will be put in parallel with the
phenomenal-reflective consciousness dynamic, in an effort to discern how the former
hypothesis relates to the already standing conceptualizations in consciousness research.
Afterwards, the emergent hypotheses generated from the marriage of the primary-secondary
theory and contemporaneous lucid dream research will be briefly described.
3. Can lucid dreaming unveil consciousness?
In point two of his wish-list of the greatest breakthroughs forthcoming in a speculated
”Golden Age” of consciousness research, Revonsuo states out precisely what is to be expected
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from lucid dreaming:
”We figure out exactly what the differences are between pure phenomenal
consciousness and reflective consciousness. One crucial experiment would be the
brain imaging of ordinary versus lucid dreaming: What happens in the brain when
phenomenal dream experience turns into reflective, self-aware dream
experience?” (Revonsuo, 2010, p. 291)
This seems very interesting indeed, but how exactly can we characterize phenomenal
and reflective consciousness from an experimental point? According to Revonsuo (2010),
phenomenal consciousness is characterized by patterns of qualities that are commonly called
sensations, percepts, emotional experiences and feelings, and sensory-perceptual images. This
immense variety of phenomenal experience goes on in dynamic patterns ever-changing and
complex, across a phenomenal field, with a vivid but limited centre that continuously changes
position against a large phenomenal background.
In contrast, reflective consciousness pertains mostly of auditory-linguistic images that
have a phenomenal surface, and also semantic content, which are symbolic expressions
referring to things outside of themselves, such as experiences in phenomenal consciousness.
Reflective consciousness is serial and limited in its capacity, as in the extreme difficulty of
expressing and formulating several explicit, completely independent trains of thought at the
same time (Revonsuo, 2010).
As far as experimental psychology is concerned, since the 1890s that consciousness was
understood via the concept of states (Voss, 2010). Accrued sleep and dream research have
shown that consciousness is, undoubtedly, state dependent (Voss, 2010). Non-lucid dreaming
appears to be a state of consciousness akin to primary consciousness and lacking frontal lobe
activation (Voss, 2010; Voss et al., 2009). Secondary consciousness may be related to frontal
lobe activation, and is present in lucid dreaming and waking state, eliciting meta-awareness in
LUCID DREAMING AND CONSCIOUSNESS 73
both (Voss, 2010; Voss et al., 2009).
In view of the research and arguments presented throughout this investigation, lucid
dreaming raises deep questions indeed, and Thompson's words formulate these questions in a
very interesting way:
”When I talk about ”my” awareness, who exactly is this self? When I say, ”I
realized I was dreaming,” who is ”I”? When I describe ”my” partial dream
control, who is the agent or controller? And how is all of this – the awareness, the
sense of self, and the feeling of agency – related to my sleeping brain and body?
To put these questions in general terms: Who or what is the experiential subject of
lucid dreaming, and how is this subject related to the brain and body?”
(Thompson, 2015b, p. 109).
According to Thompson (2015b), one finds here the necessity to distinguish between the
dreaming self and the dream ego, that is to say, between the “self-as-dreamer” and the ”self-
within-the-dream”. In a non-lucid dream, one seems to identify with his own dream ego and to
perceive, for instance, ”I'm under attack!”. Whereas in a lucid dream, one thinks: ”I'm
dreaming!”, and recognizes that the dreaming self is not the same as the dream ego. The dream
ego appears to function as an avatar within a virtual world, and the dreaming self as its user
(Thompson, 2015b).
Taking these concepts together, it would seem to the external observing academic,
following the debate and research development, that the connection between lucid dreaming
and consciousness depends on the way the phenomena of non-lucid and lucid dreaming relate to
consciousness conceptions and assumed definitions. For instance, non-lucid dreaming seems to
be interwoven with the concept of primary consciousness (Hobson & Voss, 2011), but also with
phenomenal consciousness (Revonsuo, 2010), and pre-reflective self-consciousness (Gallacher
& Zahavi, 2015). In turn, lucid dreams appear to be intertwined with the concept of secondary
LUCID DREAMING AND CONSCIOUSNESS 74
consciousness (Hobson & Voss, 2011), and yet also with reflective consciousness (Revonsuo,
2010), or reflective self-consciousness (Gallacher & Zahavi, 2015). For Thompson (2015b), it
seems to be a question of the dreaming self assimilating or not with the dream ego, and
meditative lucid dreaming, or Dream Yoga, is proposed to further study these phenomena.
One can say that these authors appear to be mentioning the same experiential plethora,
albeit with different nuances. It would seem that the continuum phenomenal-reflective
consciousness may in some ways be connected with a state consciousness continuum, a
primary-secondary consciousness continuum, a pre-reflective-reflective self-consciousness
continuum, or even an assimilation continuum between dreaming self-dream ego, where the
brain-mind relation apparently can be in some way quantifiable. Lucid dreaming fits here like a
measuring tool, capable of producing a glimpse of this continuum inner-works, in a
experimentally pliable way.
In this sense, lucid dreams may offer new perspectives for consciousness research, if
operationalized in experimental contrast with non-lucid ones. In this contrast, and in the
analysis of the transition, may lie all the nuances of the phenomenal-reflective consciousness
continuum. Starting from the non-lucid dreams, that apparently demonstrate that primary
consciousness is not specific to the wake state, including sensory imagery and the experience
with a self interacting with the dream world, while disconnected from sensory inputs and motor
outputs (Noreika et al., 2010). And all the way until reaching SVLD state, which apparently
provides rich examples of secondary consciousness, specifically of more sophisticated cognitive
and meta-cognitive processes occurring in sleep (Noreika et al., 2010). These experimental and
conceptual analyses, may provide many theoretical insights, by revealing and exposing different
segments of the continuum.
According to Noreika and colleagues (2010), when researching the transition from non-
lucid to lucid dreams, through the analysis of dream reports associated with neuroimaging
LUCID DREAMING AND CONSCIOUSNESS 75
experiments, it may become possible to map the changes in self-related processing and the
neural correlates enabling that same transition. Furthermore, the prospect of experimentally
manipulating and inducing lucid dreams may also bring forth the possibility of analysing certain
aspects of meta-awareness, such as cognitive and mnemonic processes and bodily experiences
(Dresler et al., 2014a; Noreika et al., 2010).
In addition, lucid dreams may also help investigate the neural correlates of dream
behaviour, clarifying how similar bodily experiences and dream behaviour are to their waking
state equivalents, concerning phenomenology and brain activation (Erlacher et al., 2003;
Erlacher & Schredl, 2008; Hobson, 2009a). Finally, the experimental manipulation of dream
content and induction of lucid dreams may also shine a light on the neural correlates of the
sense of agency, the first-person perspective and the narrative or autobiographical self-model
(Dresler et al., 2014a; Noreika et al., 2010).
In line with this purpose, Voss and Hobson (2015) very recently presented four
hypotheses centred around the lucid dreaming phenomenon, deduced from the empirical work
already presented in this theoretical investigation:
1. The Brain Maturation Hypothesis
2. The Hybrid State Hypothesis
3. The Space of Consciousness Model
4. The Gamma Band Hypothesis
Simply put, the brain maturation hypothesis states that lucid dreaming may be a mental
state of exception, that appears to occur in a natural way while the brain matures (Voss &
Hobson, 2015). The rationale behind this proposition is the inverse correlation between age and
lucid dream frequency, and also how difficult it is to experience this phenomenon on a regular
basis without training, both proposed in several studies (Schredl & Erlacher, 2004, 2011;
Stumbrys et al., 2014; Voss et al., 2012). Voss and Hobson (2015) suggest that the peak in
LUCID DREAMING AND CONSCIOUSNESS 76
spontaneous occurrence of lucid dreaming seems to be coincident with frontal lobe myelination
final stages, which include synaptic expansion and dendritic growth. It also attempts explaining
the origin, or the why, of lucid dreaming (Hobson, 2009b; Voss & Hobson, 2015). This is an
interesting hypothesis, and opens up an avenue of research which needs more studies, especially
with children and teenagers.
The hybrid state hypothesis posits that, when the brain shifts from a non-lucid to a lucid
dream, the subjective experience of dreaming becomes a hybrid state, with elements from both
waking and dreaming state consciousness (Hobson, 2009a; Hobson & Voss, 2015; Voss et al.,
2009). The dream self seems to simply separate from the on-going flow of mental imagery,
characteristic of non-lucid REM sleep dreaming, and the dreamer may have a variable degree of
control over the dream plot (Hobson & Voss, 2015; Voss et al., 2014). The hybrid state
hypothesis relies upon this concept, which is pointed by Voss and Hobson (2015) to be mainly
supported by empirical evidence produced by some of the previously analysed studies (Dresler
et al., 2012; Voss et al., 2009, 2014 – please refer to Part III, sub-section 2 for more details).
The Space of Consciousness (SoC) model is “based on the assumption that
consciousness is a dynamical process unfolding in a phenomenal state-space continuum” (Voss
& Hobson, 2015, p. 9). In this model, firstly proposed by Voss and Voss (2014), consciousness
is defined as a three-dimensional space (x-y-z) occupied by states that vary as a function of
sensing, judging, and motor control. Sensing (x-axis) is defined as the ability to experience
physical and mental fluctuations. Judging (y-axis) is used to describe shifting levels of higher-
order cognitive skills (meta-awareness, to think about the past, contemplate the future, make
decisions). The motor control dimension (z-axis) refers to the ability to produce body
movement. The SoC model is pointed to be solely phenomenological, as it does not differentiate
between internal and external sources of information or state-dependent neurochemical
modulations (Voss & Hobson, 2015; Voss & Voss, 2014).
LUCID DREAMING AND CONSCIOUSNESS 77
As it can be seen in figure 3, Voss and Hobson (2015) differentiate between REM lucid
dream state (equivalent to DILD) and WILD lucid dream state, as proposed by LaBerge
(LaBerge & DeGracia, 2000; LaBerge & Gackenbach, 2000; LaBerge et al., 1986). These two
states seem to differ mainly in the motor control dimension, even though this is a theoretical
proposal. This is a fascinating model, even though it may need much more refinement and
probably some more dimensions included. With the aid of this, or posterior models, it may be
possible to start positioning and placing several states of consciousness, as they are research and
more information is added.
The gamma band hypothesis pertains to the discovery of the increased activation of the
human brain frontal lobes during lucidity in dreams, in the lower gamma band (40 Hz), the how
of lucid dreaming, suggesting that brain activation in the 40 Hz frequency range relates to
secondary consciousness (Hobson & Voss, 2011; Voss et al., 2012, 2014).
At this moment in time, the path of state-dependent consciousness study is open, based
on the several hypotheses put forward through the empirical research done so far. It would seem
LUCID DREAMING AND CONSCIOUSNESS 78
that cognitive neuroscience has a puzzle with some pieces available, but many more are yet to
be retrieved. These pieces will probably fall in the SoC model, or in future versions of it. There
is still a tremendous amount of research to be done, and the model may evolve to a 3D-space in
a spheric perspective, as in a 3D-puzzle, as more axis are added to it.
4. The continuity of meta-awareness in consciousness research
One final note, linked to a relatively neglected grey area of interesting experimental
research, is due. This grey area is settled in the intersection of the body of knowledge already
obtained by sleep, non-lucid dreaming, and lucid dreaming research, with Tibetan Buddhist
experiences of Dream Yoga and Sleep Yoga.
For centuries, the notion that it is possible to become aware or lucid of one's mental
processes through the whole sleep-wake cycle, that is to say, to keep one's meta-awareness, or
continuity in consciousness, in all stages of sleep, has served as a foundation for Tibetan Dream
Yoga and Sleep Yoga (LaBerge & Gackenbach, 2000; Stumbrys, 2011; Thompson, 2015b).
Both practices aim to develop constant non-dual awareness across wakefulness, dreaming, and
dreamless sleep. It would seem that the development of awareness in dreams through Dream
Yoga would facilitate the development of awareness in dreamless sleep, and the development of
awareness in deep sleep through Sleep Yoga would in turn facilitate awareness in dreams
(Thompson, 2015b).
Presumably, through these practices it would be possible to achieve continuity of
consciousness among waking, dreaming and dreamless sleep, and this is seen in Tibetan
Buddhism as an essential step to higher personal development. Apparently, lucid dreaming may
constitute a possible glimpse in the continuity of consciousness (LaBerge & Gackenbach, 2000;
Stumbrys, 2011; Thompson, 2015b).
This would also mean that NREM lucid dreaming, or lucid witnessing, could be in
LUCID DREAMING AND CONSCIOUSNESS 79
theory achievable, thus suggesting a possible continuity in meta-awareness, or consciousness,
across the whole wake-sleep cycle (Stumbrys, 2011; Thompson, 2015b). Curiously enough,
Stumbrys and Erlacher (2012) reported two cases of lucid dreaming during NREM sleep. The
data from the two cases reported comes from another study, in which participants were
instructed to signal L-R-L-R-L-R whenever reaching lucidity. In the first case, a female (26
years), frequent lucid dreamer (≥ once a week) and with good dream recall, signalled during
NREM N2 on the second consecutive night in the sleep laboratory (during the 2nd sleep cycle,
105 mins. after falling asleep). The subject reported no presence of visual imagery, but a
floating sensation without body feeling. In the second case, also a female (26 years old),
infrequent lucid dreamer (2-4 a year) and with good dream recall, signalled also during NREM
N2 on the third consecutive night in the sleep laboratory (during the 1st sleep cycle, 95 mins.
after falling asleep). This subject did five eye signals, but had no recall (Stumbrys & Erlacher,
2012). Actually, already in 1981, LaBerge and colleagues had reported two NREM N1 lucid
dreams, and one in the transition from NREM N2 to REM (for a more detailed analysis of this
experiment, please refer to Part III, sub-chapter 2). This particular aspect is in need of a more
detailed review and further study.
In the same line, other authors (Mason & Orme-Johnson, 2010) working with
Transcendental Meditation (TM), a specific form of mantra meditation created by Maharishi
Mahesh Yogi in the mid-1950s and popularized world-wide in the 1960s and 1970s, point out
that reflective consciousness evolution may not end with lucidity, but may move further along
the continuum to a quieter, uninvolved state of awareness known as witnessing, experienced as
having no boundaries. This may be called transcendental consciousness, one that is experienced
continuously, especially during deep sleep, indicating that a higher state of consciousness has
been achieved (Mason & Orme-Johnson, 2010). Interestingly enough, Hunt and Ogilvie (1988)
had already mentioned that meditators seem to have more lucid dreams than non-meditators,
LUCID DREAMING AND CONSCIOUSNESS 80
and also that longer meditative practice appears to correlate with a higher frequency of lucid
dreams. This would need a recent study, so as to delve further into this particular aspect.
Intriguingly enough, Thompson (2015b) mentions some ancient Indian texts, called the
Upanishads, which seem to contain the first recorded map of consciousness, dating from the
sixth or seventh century (B.C.E.). The author points out that these texts put forward three
principal states of the self: the waking state, the dream state, and the state of deep and dreamless
sleep. Later texts added a fourth state, called state of pure awareness. In this literature, waking
consciousness seems to relate to the outer world and takes the physical body as the self. Dream
consciousness relates to mental images produced from memories and takes the dream body as
the self. In deep and dreamless sleep, consciousness is said to be in a dormant state not
differentiated into subject and object. The author also mentions that pure awareness seems to
witness these changing states without identifying with them or with the self that appears in them
(for more on the concept of pure awareness please refer to Thompson, 2015b). By these
standards, the lucid dreamer seems to be in the so-called state of pure awareness, in which he
observes his dream self act upon the dream, being aware that it is a dream (Thompson, 2015b).
This ancient conception is quite intriguing, as it seems to propose the hypothesis of a
continuity of meta-awareness through all the states, by means of experienced meditation, to
achieve a permanent state of self-awareness. In this ancient conceptualization, consciousness
seems to be defined as a ”light”, which illuminates or reveals things so they can be known. For
instance, in waking state it seems to illuminate the outer world, and in dreams illuminate the
dream world (Thompson, 2015b). Nonetheless, even though lucid dreams are said to be more
discontinuous with waking experience, they seem to present continuity in the sense of ”I” and
meta-awareness, that is, continuity of consciousness (Kahan & LaBerge, 1994; Stumbrys,
2011). As mentioned before, there seems to be some kind of consciousness and self-awareness
in all dreams, but non-lucid dreams seem to lack reflective or meta-awareness, contrary to lucid
LUCID DREAMING AND CONSCIOUSNESS 81
dreams, who integrate meta-awareness (Cicogna & Bosinelli, 2001; Kahan & LaBerge, 1994;
Stumbrys, 2011).
In short, the idea of continuity through the maintenance of self-awareness, meta-
awareness (and even pure-awareness), along the wake-sleep cycle is extremely intriguing. The
point is that, in cognitive neuroscience terms, and more broadly in philosophical terms, there
must be an experimental definition of what exactly is intended when the authors mention these
aspects of awareness, if a line of research including the continuity of meta-awareness is to be
pursued.
As seen before, phenomenal experience and self-awareness seem to be present in non-
lucid dreams, but meta-awareness arises only in lucid dreams. To pursue a continuity, should
one achieve meta-awareness in the whole sleep-wake cycle? Is this possible in deep sleep and
non-lucid dreams? If so, would not these states become lucid dreams, in some extent? And,
above all, would not this kind of continuity put at stake the concept of state-dependent
consciousness? Further research is needed to thoroughly understand this idea.
LUCID DREAMING AND CONSCIOUSNESS 82
Concluding remarks and bridges for the future
The notion that arises out of all concepts, empirical experimentations, and ideas put
forward previously, is that there seems to be limitations to the scientific method in coming to
terms with the felt reality of first-person experience, in the sense of a self endowed with
consciousness (Thompson, 2015b). Nevertheless, research on lucid dreaming presented
throughout this theoretical investigation clearly demonstrates the viability of empirical
experimentations under this same method. These experimentations, as far as lucid dreaming is
concerned, are limited by the low number of subjects available and able to produce SVLDs,
under different protocols. This is the first and foremost difficulty when working with this
phenomenon.
Moreover, as in everything related to consciousness studies and research, the
inescapable challenge is to have a theory that, somehow, accommodates the phenomenon. In the
case of lucid dreaming, the contemporary empirical research goes hand in hand with primary
and secondary consciousness hypothesis, which is based on a naturalistic view of human
evolution.
Another aspect, as in any branch of science, is replication. The most recent findings in
the field of lucid dreams are in sore need of experimental replication. The LuCid scale is a fine
example of this, as it is being experimentally used in adapted and shorter versions, in a very
flexible way, probably very much so. The way it was used to measure tACS results (Voss et al.,
2014) for instance, as to confirm lucidity in the 40 Hz gamma band, exposes clearly the need
for experimental consolidation in this field of research.
Furthermore, the jargon of the field needs also clarification and agreement. This is more
so in connection with consciousness research, where nomenclature abounds and several
expressions are used to refer to aspects that, in it-self, are not clearly defined. For the non-
specialist academic, the first reading moments reveal a tremendous confusion to what is what
LUCID DREAMING AND CONSCIOUSNESS 83
exactly, as each experimental research team uses its own vocabulary, and more so when
superimposed with philosophy of mind.
In what relates consciousness as a state, more research is needed in terms of mapping all
states of consciousness, so as to place them in the SoC model, or some other model that may be
presented in the near future. The continuum of states, and its inter-mixture in the mind-brain
relation should be thoroughly interpreted, so as to clarify all the gradations that go between the
experience of pure phenomenal consciousness, to the more refined state of reflective
consciousness. This may include, for instance: the last instants before death, coma, locked-in
syndrome, near-death experiences (NDEs), out-of-the-body experiences (OBEs), non-lucid
dreams, REM-initiated lucid dreams, wake-initiated lucid dreams (WILDs), meditative states
(dream yoga, sleep yoga, transcendental meditation), all the other so-called mystical or higher-
states of consciousness, and others that may be discovered in the future.
To map this continuum of states, research may pass through the merging of the sleep
laboratory with the natural environment of the dreamer, with new devices that allow for PSG
and brain imaging at home, or in a hospital facility, without wires and with the minimum
discomfort and disruption possible. These devices may also send the data through Wi-Fi, to be
processed automatically as it is happening, proceeding also to the awakenings and posterior
subjective report recordings.
In historical terms, on what investigation is concerned, there is no doubt of the
breakthrough importance of LaBerge and colleagues' 1981 experiment. This seemingly gave a
new and fresh impulse to lucid dreaming research. Throughout the 1980s and 1990s a new
surge of experimentations and writings emerged, mainly in the United States. However, this
movement apparently faltered and waned, probably due to lack of funding for new experiments.
Contemporaneously, a new resurgence seems to have happened in Germany, where the
lucid dreaming phenomenon beacon was lighted up again, espoused with consciousness
LUCID DREAMING AND CONSCIOUSNESS 84
research. The vast majority, if not all, of research involving lucid dreams seems to go on in
those latitudes, with the support of German foundations and the occasional support from Bial
foundation, in Portugal. Obviously, this needs expanding.
A golden age needs gold, which is to say, all research needs funding, and lucid dreaming
is no exception. The problem is that this particular subject is not a profitable or commercial one.
Nevertheless, one quick search on the internet reveals several sites and forums on lucid
dreaming, teeming with enthusiasts on the subject, trying to learn more and intent on dreaming
lucid. Crowd-funding may be a way of funding research, as science advances for the benefit of
all.
It would seem that, regarding the near future, several paths lead to the bridge of
replication and expansion of knowledge, which in turn leads to the field of re-doing the
experiments presented, expanding the number of subjects and consolidating the knowledge
edifice. The not so near future may involve the creation of new methods in mind, new
machinery simply put, to thoroughly map all states of consciousness in a way that enables us to
finally comprehend where all pieces fit, and how the whole picture of state consciousness looks
like.
Lucid dreaming came a long way, from an obscure and suspected phenomenon,
mentioned only in rare under pseudonym-written books and manuscripts associated with
mystiques and the occult, to an identified and clearly established phenomenon in the scientific
journals of the academic world. Suffice to say that this new consciousness state, embedded in
REM sleep, may hold one of the contemporaneously available keys for consciousness research,
and for navigation on the vast ocean of human subjectivity.
LUCID DREAMING AND CONSCIOUSNESS 85
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Appendix A
Interview questions regarding dream recall and frequency of lucid dreams (Voss et al., 2012, p.
635)