Sleep Physiology Flashcards
What is sleep?
normal, recurring reversible state with loss of ability to respond to the external environment
When does NREM sleep occur?
start of the night
3/4 of sleep in young adults
What EEG changes are seen in NREM sleep?
synchronised, rhythmic EEG activity
partial muscle relaxation
reduced cerebral blood flow
When does REM sleep occur?
mostly at end of the night
What EEG changes are seen in REM sleep?
fast activity, fMRI shows increased brain activity similar to wakefulness
When does narrative dreaming occur?
REM sleep
What happens in deep sleep?
the cortex recovers
Which drugs suppress REM sleep?
tricyclic antidepressants
Is Rem sleep essential?
mainly for easy brain development
suppressed REM sleep has no effect
What is the sleep pattern of neonates like?
16 hours a day asleep
50% REM sleep, shorter cycles
What is sleep patterns in elderly like?
increased awakenings
reduced REM latency
reduced total sleep time
daytime napping
What kind of rhythm controls sleep-wake, appetite and hormone secretion?
Circadian rhythm
In which type of sleep is memory consolidated?
REM sleep
When is cortisol level highest?
Early morning when waking
When is cortisol level lowest?
sleep - midnight
How long does normal Circadian rhythm last?
24:20-25 hours
What cells are involved in regulating the body clock?
non-rod, non-cone cells
Which phase of sleep does protein synthesis and cell division happen?
NREM sleep
Does sleep help with tissue repair? OR muscle repair?
tissue yes
muscle no evidence
What happens to the brain in sleep deprivation?
irritable and suspicious
visual illusions
micro sleeps
concentration lapses
What is the normal acceptable amount of sleep?
7-7.5 hours
What does a 15 minute afternoon nap equate to in overnight sleep?
90 mins
What are some examples of non-REM parasomnias
non-dreaming confessional arousals sleep walking sleep terrors and paralysis restless legs bruxism
What is bruxism?
grinding teeth and clenching jaw
What are some examples of REM parasomnias?
dreaming, simpler behaviour, latter third of the night
Which part of the night do REM parasomnias occur?
latter third
Which condition commonly has REM sleep parasomnias preceding clinical features?
Parkinson’s
How does Narcolepsy present?
daytime sleepiness cataplexy hypnagogic hallucinations sleep paralysis RBD
What is cataplexy?
loss of muscle tone triggered by emotion
What are hynagogic hallucinations?
hallucinations at sleep onset
What effects can narcolepsy have on an individual?
reduced academic and social performance
loss of jobs
increased risk of RTA
What investigations can be useful in narcolepsy?
overnight polysomnography
multiple sleep latency test
Why is Lumbar Puncture useful in Narcolepsy patients?
CSF hypocretin levels below 110pg/ml are consistent with narcolepsy
