Sleep disorders Flashcards
What is sleep?
Normal, recurring, reversible state.
Loss of ability to respond to external environment
Not conscious but not unconscious i.e. can respond when stimulated
What is REM sleep?
Rapid eye movement (REM) sleep mostly occurs at end of night
EEG shows fast activity, fMRI shows increased brain activity
Atonic muscles (except diaphragm and extraocular muscles)
Cerebral blood flow increased, impaired thermal regulation
Narrative dreaming
What is non-REM sleep?
Non-REM sleep at start of night (3/4 of sleep in young adults is N-REM)
Synchronised, rhythmic EEG activity, partial muscle relaxation, reduced cerebral blood flow
Reduced HR, BP and tidal volumes
Some non-narrative images
What kind of sleep is essential and what kind isn’t?
Deep sleep is essential - allows the cortex to recover
REM sleep is mainly for early brain development, likely dispensable - tricyclics suppress REM sleep with no effect, so can’t be essential
How much sleep do neonates get and what kind of sleep is it? How does this change with age?
Neonates spend 16 hours per day asleep - 50% REM sleep
During 1st decade, %REM sleep falls, REM latency increases
Elderly - increased awakenings, reduced REM latency and total sleep time and daytime napping
What controls sleep?
Biology and physiology - circadian rhythm important for sleep-wake, appetite, hormone secretion
Normal circadian rhythm lasts 25 hours
Light entrains body clock - uses retinal ganglion cells projecting to suprachiasmatic nucleus
What is the link between exercise and sleep?
Endurance is reduced with lack of sleep
No evidence of muscle recovery during sleep however, sleep does help with tissue repair due to sleep related GH release
Cell division peaks during sleep
What are the effects associated with no sleep?
Visual illusions, microsleeps and concentration lapses, irritability, impaired alertness - doesn’t affect routine behaviour, old and well rehearsed acts or logic tasks
What are the features of non-REM parasomnias?
Non-dreaming, confusional arousals, sleep walking, sleep terrors and paralysis, bruxism (teeth grinding), restless legs and periodic limb movement in sleep (PLMS)
What are the features of REM parasomnias?
Often seen preceding PD, dreaming, much simpler behaviour, usually latter 1/3rd of night
When does narcolepsy typically present?
Two peaks in onset - 15 and 36
How does narcolepsy present clinically?
Daytime sleepiness - involuntary sleep during eating/talking, may be severe and impossible to resist
Cataplexy - present in 70% of patients, loss of muscle tone triggered by emotion
Hypnagogic hallucinations - hallucinations occurring at sleep onset
Sleep paralysis
RBD - recurrent brief depression
What investigations can be used for narcolepsy?
Overnight polysomnography
Multiple sleep latency test - 4x25 minute naps scheduled 2 hours apart., record of EEG, muscle activity and eye movement., measures time from the start of a nap to the first signs of sleep (latency)., faster the patient falls asleep the sleepier they are
Lumbar puncture - low CSF hypocretin levels are consistent with narcolepsy
