Sleep Flashcards
what is sleep?
a readily reversible state of reduced responsiveness to, and interaction with, the environment
what are the two types of sleep?
Non-REM, REM
what is the definition of non-REM sleep?
Idling brain in a movable body
what are the features of non-REM sleep?
slow, large amplitude
what are the EEG features of non-REM sleep?
- Partial relaxation of muscles
- Temperature and energy consumption are lowered
- Increase in parasympathetic
- Some non-narrative images
what are the 4 types of non-REM sleep?
N1, N2, N3, N4
what is the features of N1 sleep?
between sleep and wakefulness, brain produces theta waves, hypnagogic hallucinations (hearing and seeing things that aren’t there, repetitive movements. Boat, Tetris effect, falling), only lasts a few mins
what is the features of N2 sleep?
harder to awaken, more theta waves, sleep spindles (bursts of rhythmic brain activity – inhibit cognitive processes), K complexes (suppress cortical processes and help with memory processing), lasts 5-15 mins
what is the features of N3 sleep?
slow wave sleep, delta waves
what is the features of N4 sleep?
large EEG rhythms very difficult to wake up, sleep walking and talking
what is the function of non-REM sleep?
protein synthesis, cell division and growth, body repair + restoration
what is the definition of REM sleep?
active, hallucinating brain in a paralysed body
what are the features of REM sleep?
• Fast, low voltage fluctuations EEG activity, fMRI shows increased brain activity
what are the features of REM sleep?
Brain activity similar to wakefulness
Atonic muscles (total paralysis) - except diaphragm and extraocular muscles
Dominant control via sympathetic system
Narrative dreaming
what does parasympathetic stimulation in Non-REM sleep cause?
reduced cerebral blood flow, reduced heart rate, blood pressure and tidal volumes
what does sympathetic stimulation in REM sleep cause?
Cerebral blood flow increased, impaired thermal regulation, heart rate irregular
what is the function of REM sleep?
consolidates memory, deletes unnecessary memory files, maintains immunocompetence, conserve energy in high metabolic species
what is the order of a sleep cycle?
N1 → N2 → N3 → N2 → REM → N1 = Repeat
how long is an average sleep cycle?
90mins
what is the average split of REM to Non-REM?
75% NREM 25% REM
what neurons are responsible for control of sleep?
diffuse modulatory neurotransmitter systems
what brain stem modulators enhance REM sleep?
acetylcholine
what controls the EEG rhythms of the brain?
Thalamus
what is the pattern of sleep tendency?
2 peak
how long is the circadian rthythym?
25 hours
what is the cause of narcolepsy?
- CNS Pathology – trauma, stroke, tumours, infection, cysts, MS
- Genetics – HLA
- Sporadic
what are the clinical features of narcolepsy?
daytime sleepiness cataplexy Hypnagogic hallucinations Sleep paralysis RBD
how is narcolepsy diagnosed?
Overnight polysomnography
Multiple sleep latency test
Lumbar puncture - CSF hypocretin
what is the pathophysiology of narcolepsy?
- Cholinergic hypersensitivity
- Serotonin or noradrenaline pathway-specific dysfunction
- Dopamine pathway dysfunction
- CNS histamine deficiency
- Hypocretin (orexin) pathway dysfunction
what is the management of Adults with Narcolepsy?
o Sleep hygiene + lifestyle changes (non-pharmacological treatment)
o CNS stimulants alone or in combination – modafinil, armodafinil, methylphenidate, dexamfetamine, sodium oxybate, methamphetamine
what is the management of adults with cataplexy?
o Avoidance of triggers + sodium oxybate and/or antidepressants
o Monoamine oxidase inhibitors
what is the management of Children with narcolepsy?
o Sleep hygiene + lifestyle changes
o Modafinil or methylphenidate
what is the management of Children with cataplexy?
o Avoidance of triggers + antidepressants – fluoxetine, venlafaxine, clomipramine
