Sleep Flashcards
what is sleep?
Normal, recurring reversible state
Loss of ability to respond to external environment
are you conscious or unconscious during sleep?
not conscious - as not fully aware of self and environment
but not unconscious as can respond when stimulated
what happens in non-REM sleep?
Synchronised rhythmic EEG activity, partial muscle relaxation of muscles, reduced cerebral blood flow
Reduced heart rate, blood pressure and tidal volumes
Some non-narrative images
Often causes you to wake up suddenly, not quite remembering what happened, with a strong emotion
when does non-REM sleep usually occur and how much of sleep does it make up?
more at start of night
3/4 of sleep in young adults
features of REM sleep?
EEG shows fast activity, fMRI shows increased brain activity (similar to wakefulness)
Atonic muscles (except diaphragm and extraocular muscles)
Cerebral blood flow increases, impaired thermal regulation
Narrative dreaming
when does REM sleep occur and what is its function?
mostly at end of night
mainly for early brain development
dispensable sleep
what type of sleep is most important?
Non-REM sleep
REM sleep only really important in childhood
Deep sleep is essential sleep
Only part of lost sleep regained after sleep loss
allows cortex to recover after long day
how do sleep patterns differ in young and elderly?
neonates - sleep 16 hrs per day (50% REM) children (1st decade) - reduced REM - increased REM latency - sleep earlier and wake later adolescents - delayed sleep pattern (sleep and wake later) elderly - sleep and wake earlier - increased awakenings - reduced REM latency and total sleep time
what 3 things contribute to causing onset of sleep?
homeostatic response (longer time awake = more sleepy) emotional response (brain has to be prepared for bed, feeling unrefreshed after long sleep as brain doesn't really switch off, remains in semi-vigilant state) circadian rhythm
what is circadian rhythm?
2 peaks of sleepiness in a day (4-6AM and 2-4PM)
important for sleep-wake, appetite and hormone secretion
normal rhythm lasts 24-25 hrs
what influences circadian rhythm and body clock?
bright light
retinal ganglion cells projecting to suprachiasmic nucleus
non-rod and non-cone cells involved
how does psychology control sleep?
it doesn’t
biology and psychological factors control sleep
how does sleep influence exercise?
sleep deprivation causes reduced endurance (due to psychological factors)
GH release and cell division peaks in sleep
how does sleep influence muscle recovery and tissue repair?
doesn’t affect muscle recovery
helps tissue repair
how does sleep affect brain?
cortex cannot fully reset when awake
more complicated cortices require more sleep to reset
how can lack of sleep effect the prefrontal cortex?
no psychoses but often become irritable and suspicious
visual illusions
microsleeps and concentration lapses
does lack of sleep affect prefrontal functioning?
no
deals with old and well rehearsed tasks and routine behaviour
how is sleep deprivation most likely to kill you?
human error
- e.g road accidents
how much sleep is adequate?
7-7.5 hrs hrs is acceptable (minimum)
A mid afternoon nap of 15 mins is equivalent to 90 mins overnight (best to be around 2pm)
Long lie at the weekend will not make up for chronic sleep deprivation during the week
features of REM parasomnia?
Body not relaxed as it should be in REM, so body acts out dreams
Much simpler behaviour
Usually latter 1/3 of night
Often have preceding parkinsons
features of non-REM parasomnia?
non-dreaming
causes confusional arousal, sleep walking, sleep terrors and paralysis
give an example of non-REM parasomnia and why this occurs?
waking up suddenly to a loud noise and body reacts/jumps up but you don’t really remember doing it
due to fact that primitive part of brain wakes up first
what is narcolepsy?
REM behavioural disorder
features of narcolepsy?
severe daytime sleepiness (involuntary and during eating/talking etc)
cataplexy
hypnagogic hallucinations (hallucinations at sleep onset)
sleep paralysis
RBD
how is narcolepsy diagnosed?
polysomnography multiple sleep latency test - fall asleep in 10 mins - very fast onset of REM sleep) lumbar puncture (low CSF hypocretin levels)
