Sleep

Question 1

what is sleep?

Answer 1

Normal, recurring reversible state

Loss of ability to respond to external environment

Question 2

are you conscious or unconscious during sleep?

Answer 2

not conscious - as not fully aware of self and environment

but not unconscious as can respond when stimulated

Question 3

what happens in non-REM sleep?

Answer 3

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

Question 4

when does non-REM sleep usually occur and how much of sleep does it make up?

Answer 4

more at start of night

3/4 of sleep in young adults

Question 5

features of REM sleep?

Answer 5

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

Question 6

when does REM sleep occur and what is its function?

Answer 6

mostly at end of night
mainly for early brain development
dispensable sleep

Question 7

what type of sleep is most important?

Answer 7

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

Question 8

how do sleep patterns differ in young and elderly?

Answer 8

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

Question 9

what 3 things contribute to causing onset of sleep?

Answer 9

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

Question 10

what is circadian rhythm?

Answer 10

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

Question 11

what influences circadian rhythm and body clock?

Answer 11

bright light
retinal ganglion cells projecting to suprachiasmic nucleus
non-rod and non-cone cells involved

Question 12

how does psychology control sleep?

Answer 12

it doesn’t

biology and psychological factors control sleep

Question 13

how does sleep influence exercise?

Answer 13

sleep deprivation causes reduced endurance (due to psychological factors)
GH release and cell division peaks in sleep

Question 14

how does sleep influence muscle recovery and tissue repair?

Answer 14

doesn’t affect muscle recovery

helps tissue repair

Question 15

how does sleep affect brain?

Answer 15

cortex cannot fully reset when awake

more complicated cortices require more sleep to reset

Question 16

how can lack of sleep effect the prefrontal cortex?

Answer 16

no psychoses but often become irritable and suspicious
visual illusions
microsleeps and concentration lapses

Question 17

does lack of sleep affect prefrontal functioning?

Answer 17

no

deals with old and well rehearsed tasks and routine behaviour

Question 18

how is sleep deprivation most likely to kill you?

Answer 18

human error

- e.g road accidents

Question 19

how much sleep is adequate?

Answer 19

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

Question 20

features of REM parasomnia?

Answer 20

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

Question 21

features of non-REM parasomnia?

Answer 21

non-dreaming

causes confusional arousal, sleep walking, sleep terrors and paralysis

Question 22

give an example of non-REM parasomnia and why this occurs?

Answer 22

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

Question 23

what is narcolepsy?

Answer 23

REM behavioural disorder

Question 24

features of narcolepsy?

Answer 24

severe daytime sleepiness (involuntary and during eating/talking etc)
cataplexy
hypnagogic hallucinations (hallucinations at sleep onset)
sleep paralysis
RBD

Question 25

how is narcolepsy diagnosed?

Answer 25

polysomnography
multiple sleep latency test
- fall asleep in 10 mins
- very fast onset of REM sleep)
lumbar puncture (low CSF hypocretin levels)