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Ultradian Rhythm and Sleep Deprivation Studies
This would be our sleep cycle, there are 5 stages of sleep:
1) Stage 1 person becomes relaxed and drowsy
2) Stage 2 EEG waves become slower and larger quite easy to be woken up in this stage
3) Sleep depends EEg waves are slow and large
4) Stage 4 a.k.a. SWS or `deep sleep', body temp drops, growth hormone secreted now
5) Stage 5 REM sleep, EEg indicates that brain is active.
REM sleep decreases with age as sleep progresses REM increases in quantity and stage 4 decreases and is gone by
A person sleeps in this pattern of stages (most people have 5 cycle a night):
cycle 1: 1,2,3,4,3,2,5 cycle 2: 2,3,4,3,2,5
Muscles experience "Virtual paralysis" twitches occur during REM therefore muscles are active.
Sleep Deprivation Studies
Stayed awake for 8 days suffered from hallucinations, severe delusions and low body temp consequences lasted for
years and his mood was negatively affected for the long term.
Generalising is hard because of individual differences (sleep cycles vary), BUT we have biological similarities
Nat Obs study low control, (C&E), indiv diff
Short term is more affected, long term conseq. were more ambiguous. Other factors may have caused his bad
Aged 17, stayed awake for 11 days. Suffered disorganised speech and blurred vision with small degree of paranoia.
Afterwards, slept for 15hrs, recovered 70% of his stage 4 sleep and 50% of stage 5 sleep (REM).
Can't generalise because of indiv diff and his age and gender might alter results BUT does provide a representative.
Stage 4 and 5 sleep are imperative in order to function and if lost can be mostly regained possibly that stage 4
sleep more important than stage 5.
Lugaressi et al (1986)
Studied 56yr old man who had a genetic defect meaning he could never sleep due to damaged parts of brain he eventually
There is something vital that our brains and bodies go through when we sleep, like growth or healing, without sleep
we evidently can't function.
Can't see C&E because he could have had an undetectable illness, and one of the symptoms was no sleep.
Rechtschaffen et al (1983)
Rats on discs on water: EEG activity monitored to tell when they were about to fall asleep. When one rat was nearly
asleep the disc rotated had to stay awake otherwise it would fall in the water. The control rat sat on a rotating disc but
stopped when it was falling asleep. The rat that was not allowed to sleep died in 33 days.
Suggests that the importance of sleep is universal to all animals
Unethical study no protection from harm as the rats died.
Can't generalise to humans: rats and humans might have different sleep cycles, humans might cope better.
Lab exp, highly controlled (C&E), but extraneous variables (disease? Stress?) not accounted for.
Partial sleep deprivation
Placed upturned flower pots in tanks of water. Cats had to sit on pots when in NREM they stayed in pots, but in REm
they lost muscle tone so fell in and woke up. Deprived of REM sleep. Cats soon died.
REM sleep is vital for rejuvenation of brain/ body and is clearly one of the crucial stages.
Cats and humans might rely on stages differently i.e. REM cycles less important for humans, can't gen.
Unethical PFH. Is study justified? Does the end justify the means?
Lab exp, C&E, highly controlled, but extraneous variables can't be seen.
Webb and Bonnet (1978)
Deprived Pps of sleep gradually. Over 2 month period, they cut their sleep down to 4hrs a night with no apparent effects.
Suggests that stages can be reduced, and in the first 2hrs we've had all stage 4 sleep anyway, implies stage 4
sleep is most important.