dement & kleitman (1957)
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The relation of eye movements during sleep to dream activity: An objective method for the study of dreaming.
Dement & Kleitman (1957)
SLEEP It is an interesting topic and it has been
usually studied by medicine.
The better way to investigate this issue, is using electroencephalography (EEG) measuring brain activity during sleep.
This usually gives an idea of the “structure” of sleep during the night.
SLEEP1. NREM SLEEP (9-130 mins)
Each stage
STAGE 1: (hypnagogic stage)•Transition state between
being awake and sleeping. • Eyes move more slowly • Muscle activity and heart rate
slow down. • Light sleep where you can be
awakened easily• Relaxation stage drowsiness
STAGE 2:• Movement stops • Brain waves become slower
with an occasional burst of rapid brain waves.
•At this point, the body prepares to enter deep sleep.
SLEEPSTAGE 3- Extremely slow brain waves (delta waves)
-Combined with smaller, faster waves called theta waves.
STAGE 4- Deepest sleep. - No eye movement or muscle activity - Brain produces more delta waves than theta waves. - In Stage 4, some may experience sleepwalking or night terrors.
REM SLEEP (rapid eye movement)
STAGE 5- Breathing becomes more rapid- Eyes move rapidly - Muscles are temporarily paralysed. (to protect from acting out) Heartbeat may increase and muscles may experience occasional muscular twitches. - REM usually takes place 90 minutes after falling asleep.
Normal sleep cycle: Stages 1, 2, 3, 4, 3, 2, REM
BACKGROUND AND CONTEXT
Dreaming and sleep are closely related, but only recently it’s been studied scientifically.
It is a very interesting topic, and has caught the attention of many scientists.
Sleep deprivation one of the ways of studying sleep.
BACKGROUND AND CONTEXT
Scientific study of dreams physiological variables using a reliable scientific method to determine exactly when dreaming occurs.
Self report there is no other way of proving dreaming occured.
Self reports + physiological techniques to measure phenomena reliable and objective
BACKGROUND AND CONTEXT
Aserinsky + Kleitman first to study relationship between REM and sleep
They discovered that high dream recall in participants woken up during REM.
They confirmed the relationship between
REM + SLEEP + DREAMING
BACKGROUND AND CONTEXT
They also discovered that there was a cyclic process depth of sleep changed during the night
AIM AND NATURE This study shows the results of
a rigorous testing of the relationship between eye movement and dreaming.
Hypotheses:1. There is a significant
relationship between REM/NREM sleep and dreaming, such that (based on previous research).
REM sleep is associated with dreaming and NREM, isn’t.
AIM AND NATURE 2. There is a significant
positive correlation between the subjective estimate of the duration of dreams, and the length of eye movement period prior to awakening.
3. There is a significant association between the pattern of eye movement and the content of the dream. Eye movement reflects the visual experience of the dream.
METHOD / DESIGN 7 adult males / 2 adult females Studied under controlled lab
conditions 1 night in the sleep lab being woken
at various intervals
Physiological recordings were made of: Changes in corneoretinal potential
fields as the eyes moved Brainwaves (as a criterion of depth
of sleep)
METHOD / DESIGN Two or more electrodes
were attached near the eyes
Two or three attached to the scalp.
Participants were woken by the ringing a doorbell near the bed for them to wake up.
METHOD / DESIGN Participants had to speak
into a recording device near the bed and say: Whether or not they had
dreamt If they could, relate the
content of the dream
No communication between participants and the experimenter until it had been judged that the participant had been dreaming.
How did they know participants had really dreamt?
They had to give a coherent, fairly detailed description of dream content.
Only then the experimenter could enter the room and ask for details.
Participants didn’t know if they were woken from a REM or NREM sleep.
RESULTS/ FINDINGS REM sleep basically had low voltage relatively
fast EEG pattern.
RESULTS/ FINDINGS In between REM periods EEG indicated
deeper sleep They were either
High voltage Slow activity Or frequent
No REMs were observed during the initial moments of sleep
RESULTS/ FINDINGS REM uninterrupted periods lasted between 3-50
minutes (mean 20) They tended to increase the later in the night they
occurred
The eyes didn’t move with a constant pattern they occurred in bursts of 1, 2 to 100 movements
A single movement lasted 0.1-0.2 seconds and followed by a fixation pause of varying duration.
RESULTS/ FINDINGS The REM periods occurred quite frequently during the night
average every 92 minutes.
Awakenings during the night:
Despite the awakenings, sleep was similar to uninterrupted sleep.
HOURS %First 2 hours 21Second 2 hours
29
Third 2 hours 28Fourth 2 hours
22
RESULTS/ FINDINGSHYPOTHESIS 1 Participants uniformly showed a high incidence of dream recall
following REM awakenings, and a low incidence following NREM awakenings.
When REMs stopped, the incidence of dream recall dropped dramatically. Within 8 mins after REM ended in 17 awakenings 5
dreams were recalled Within more than 8 mins after NREM 132 awakenings 6
dreams were recalled.
RESULTS/ FINDINGS Participants were more confident
they hadn’t dreamed, after NREM
When aroused during deep sleep they were confused and they felt they must’ve been dreaming but they didn’t remember the dream.
When participants couldn’t recall a dream following REM sleep, this was usually in the first two hours.
RESULTS/ FINDINGS HYPOTHESIS 2
Participants were woken after 5 or 15 mins after REM, and based on their recall of the dream, they had to decide which was the correct duration.
All but one could do this accurately
Significant correlation between minutes of REM and lengths of dream narratives (words)
RESULTS/ FINDINGS HYPOTHESIS 3 it was hard to
know the direction in which Ps were looking when dreaming.
They were woken up as soon as a pattern of eye movement persisted for at least a minute. Mainly vertical Mainly horizontal Vertical and horizontal Very little or no movement.
RESULTS/ FINDINGS Of 35 awakenings only 3
periods of only vertical or only horizontal.
There were several dreams and usually eye movement corresponded to what was happening in the dream.
In participants with mixed movements usually they were looking at a moving object close to them.
CONCLUSIONS Each of the 9 participants had regularly
REM periods during the night.
As predicted:
1. High incidence of dream recall ocurred when participants were woken up after REM. Low for NREM.
2. When a series of awakenings ocurred either 5 or 15 minutes after REMs had began, participants judged the correct dream duration very accurately.
3. The pattern of REMs was related to the visual imagery of the dreams.
Recording REMs during sleep objective measure of dreaming.
EVALUATION: Methodological issues
Beaumont being woken from NREM dream may lead to forgetting more than with REM
In REM sleep the brain is more active
This could be a major confounding variable that could make all these results to be questionable easily.
Herman there is no considerable difference in dream report between REM and NREM.
Foulkes: saying that REM=dreaming and NREM = non dreaming oversimplification
Although only 5-10% of NREM sleepers reported dreaming, 70% could report dream like impressions.
Besides, dreaming is also established to occur during the hypnagogic period and daydreaming.
Theoretical issues One of the great questions of
psychology is “is dreaming useful?/necessary?”
Should sleep be seen as active or passive?
Sleep is an active process not a consequence of neuronal fatigue.
The brain of a sleeping person is almost as active as the one from a person who’s awake.
SLEEP IS AN ACTIVE PROCESS
Theoretical issues Evidence has been been found for the relationship
between REM sleep and dreaming rem rebound phenomenon.
REM rebound: When people are deprived from REM sleep, the next night they “make up” for it. Compensation.
Dement: when participants were deprived from REM sleep irritable, nervous, unable to concentrate, paranoid, hallucinations, etc.
These symptoms were very possibly, consequence of Dement’s own expectations he told the Ps that this experiment could have consequences and had an available psychiatrist.
Theoretical issues Dement replicated the study and
found no evidence for psychiatric impairment in REM deprived Ps.
He also found evidence for the REM rebound
Then, possibly REM and dreaming are the most important functions of sleep.
Subsequent research 1990’s There was a change in the vision of
dreaming and REM. Dreaming appeared to be a continuous process
that also occurred during NREM periods.
NREM dreams shorter and more rationally constructed.
REM dreams more emotional and more detailed.
Subsequent research Researchers
questioned if really REM was necessary for dreaming to take place
At some point, REM sleep was linked to a brain structure called PONS (research with kittens)
Subsequent research But, evidence: people with problems in PONS
dreamt anyway.
Or people who said they had never dreamed, but had an intact pons, even though they went through REM phases.
But they had lesions in other brain structures. What is clear for this research Dream takes place independently of REM and the pons.
Subsequent researchHobson’s Activation-Synthesis
model: “REM-ON” area located in the pontine
reticular formation ACTIVATION REM sleep
This prevents most sensory information from reaching the brain.
The switch from the motor cortex is switched off, causing the person to be paralysed during REM sleep.
Other structures associated to memory and emotion are activated
In summary When REM sleep occurs:
REM-ON area: Activation (ON)
Motor cortex OFF
Memory and emotion structures ON (probably hippocampus and amygdala)
Subsequent research Dreaming occurs when these systems
activate simultaneously and are syntethized similar to a waking brain
In a waking brain
+ + + +
SENSORY INFORMATION
MOTOR INFORMATION
EMOTIONAL INFORMATION MEMORY
SENSE OF
REALITY
This information is presented in an ordered way when we are awake
Subsequent research In dreams information doesn’t
follow a logic order weird dreams The internal processes involved
in dreaming are random.
Dreams normally involves activity from the visual and motor systems.
Many dreams could be understood based on body experience erotic dreams, flying, etc, related to certain organs.
Subsequent research Reverse learning
(Crick&Mitchison) we dream in order to forget.
A complex associational network overloaded of incoming information creation of false thoughts.
These thoughts might be outdated but persistent.
REM sleep could be erasing those thoughts (unlearning)
Subsequent research Crick & Mitchison
trying to record our dreams isn’t a good idea. They are ideas we’re trying to get rid of!
This model only applies to bizarre dream content. And what about narrative?
This is better understood as dreaming to reduce fantasy or obsession.
Subsequent research The activation-synthesis
model refers to the where but not to the why or what for.
Here is where psychological (psychodynamic) perspectives come into play Freud
Freud’s theory of dreams
1900 The interpretation of dreams (S.Freud)
“Todo sueño es cumplimiento de deseo”.
Dream usually manifest certain ideas or experiences that weren’t elaborated during the day (restos diurnos)
2 types of content: Manifest content: the story or
narration itself Latent content: the meaning
(underlying)
Applications and implications
In animals, REM sleep may have evolved to access repeatedly the information useful for survival (location of food, etc)
To mantain sleep movement had to be suppressed (motor neurons) otherwise you wake up!
Eye movement wasn’t enought to wake up, so there is still access to visual information that, combined with past experience strategy for behaviour.
It might be adaptive
Applications and implications
In humans… It could be that the crucial
information for survival is the basic information in the unconscious.
We have language, animals don’t. Information is basically visual we inherited it?
But this information for us, could be useful. That’s why we remember dreams.
We dream more under stress related to difficulties. They are EMOTIONAL.
Applications and implications
Usually in mood disorders, there are alterations of sleep.
Babies have more REM sleep this suggests that maybe one of the functions of brain activation is the developing of the brain itself.
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