Neuroscience Optional Lecture

Sleep - a brief introduction

What is sleep?

• Sleep is a naturally recurring state of mind andbody characterized by altered consciousness,relatively inhibited sensory activity, inhibitionof nearly all voluntary muscles, and reducedinteractions with surroundings.

McMillan Medical Dictionary

Sleep studies

• The EEG is frequently used in the investigation of sleep disorders especially sleep apnoea.

• Polysomnography : EEG activity together with – heart rate,

– airflow,

– respiration,

– oxygen saturation and

– limb movement

Sleep patterns of EEG

• There are two different kinds of sleep:• Rapid eye movement sleep (REM-Sleep)

• Non-REM sleep (NREM sleep)/ slow wave sleep

• NREM sleep is again divided into 4 stages (I to IV). The EEG pattern in sleep is given in the following table:

Standard somnographic montage

Stage 1• Brain activation level reduced: low voltage EEG,

diminished

• alpha activity, reduced frequency activity (theta) 3-7 Hz

• EOG – Slow eye movement, low muscular activity

• EMG moderate – reduced

Stage 2

• low voltage EEG, mixed activity frequency, 12-14 Hz

• sleep spindles associated with K complexes (diphasic

• waves, > 0,5 s)

• EOG – slow, rare eye movements

• EMG moderate – reduced muscular activity

Stage 3

• EEG –delta waves, 0,5-2 Hz & amplitude

• >75mV; covering around 20-50% from the

• analyzed epoch.

• EOG – rare eye movements

• EMG moderate – reduced muscular activity

Stage 4

• EEG delta activity covering >50% from the epoch

• EOG – rare eye movements

• EMG moderate - reduced

REM Stage

• EEG low voltage, rhythm with rapid activity

• and mixed frequencies (desynchronized

• sleep), aspect close to stage 1

• EOG – REM, mirror aspect

• EMG – muscular activity absent

Changes in brain waves during different stages of sleep & wakefulness

Neurocircuitry of sleep induction and sleep maintenance

A simplified representation of sleep-wakeneurocircuitry shows the major braincenters and neuroendocrineparameters involved. Thick arrowsrepresent active pathways during sleep.The absence of daylight leads to a netinhibition of excitatory efferentprojections to central and peripheralsystems active during wakefulness.Green arrows are excitatory pathways,red are inhibitory pathways.Abbreviations: 5-HT-Serotonin, Ach-Acetylcholine, ACTH -Adrenocorticotropic hormone, AD-Adrenaline (Epinephrine), Cort-Cortisol,CRF-Corticotropin-releasing factor, DA-Dopamine, DMH-Dorsal medialhypothalamus, DRN-Dorsal raphenucleus, GABA-Gamma-aminobutyricacid, Glut-Glutamate, HA-Histamine,HCRT-Hypocretin (orexin) neuropeptideprecursor, LC-Locus ceruleus, LH-Lateralhypothalamus, Mela-Melatonin, MRN-Medial raphe nucleus, NE/NA-Norepinephrine/Noradrenaline, PVN-Paraventricular nucleus, RVLM-Rostralventrolateral medulla, SCN-Hypothalamic suprachiasmatic nucleus,TMN-Tuberomammillary nucleus,VLPO-Ventral lateral preoptic area,VTA-Ventral tegmental area

https://neuroendoimmune.wordpress.com/2013/11/19/what-do-you-do-when-counting-sheep-just-doesnt-cut-it-look-at-neurocircuitry/

Reticulate ascendent activatorysystem-cholinergic (ACh) neurons -upper pons, the pedunculopontine(PPT) -laterodorsal tegmental nuclei (LDT).-tuberomammillary nucleus (TMN)

-histamine (His)-the ventral periaqueductal gray matter (vPAG) -dopamine (DA),-serotonin (5-HT), -locus coeruleus (LC) -noradrenaline (NA)-lateral hypothalamus (LHA)-hypocretin/orexin (ORX) -melanin-concentrating hormone (MCH)-basal forebrain (BF) neurons that contain GABA or ACh. (Saper et al (2005))

http://neurowiki2013.wikidot.com/individual:neurotransmitter-system-and-neural-circuits-gover

Sleep pathway -The ventrolateral preoptic nucleus (VLPO) -the tuberomammillary nucleus (TMN)-the ventral periaquaductal gray matter (vPAG)-the locus coeruleus (LC)-lateral hypothalamus (LHA; green), -perifornical (PeF) -orexin (ORX) -cholinergic (ACh) -the pedunculopontine (PPT)-laterodorsal tegmental nuclei (LDT). (Saper et al(2005))

http://neurowiki2013.wikidot.com/individual:neurotransmitter-system-and-neural-circuits-gover

• http://www.lifeextension.com/magazine/1997/3/report/page-01?p=1

• Gotter et al, 2012

Imagine: http://en.wikipedia.org/wiki/Sleep_deprivation

Why do we sleep?

Glymphatic system

Tarasoff-Conway et al, 2016

Why do we dream?

• EXERCISE !!!!

• http://www.psychiatrictimes.com/sleep-disorders/role-melatonin-circadian-rhythm-sleep-wake-cycle

• Non-rapid eye movement (NREM) parasomnias– Confusional arousals– Sleepwalking (somnambulism)– Sleep terrors (night terrors)– Teeth grinding (bruxism)– Restless legs syndrome & periodic limb

movements– Sleep sex– Sleep related eating disorder (SRED)

• REM parasomnias– REM sleep behavior disorder– Recurrent isolated sleep paralysis– Catathrenia

Sleep paralysis

Hirshkowitz et al, 2015

How much sleep do we need?

• Newborns (0–3 months)14 to 17 hours

• Infants (4–11 months)12 to 15 hours

• Toddlers (1–2 years)11 to 14 hours

• Preschoolers (3–4 years)10 to 13 hours

• School-age children (5–12 years) 9 to 11 hours

• Teenagers (13–17 years) 8 to 10 hours

• Adults (18–64 years) 7 to 9 hours

• Older Adults (65 years and over) 7 to 8 hours