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Restoration Theories & Ecological explanations of sleep
Oswald (1980) Sleep as an aid to physical recovery
Argued that SWS is needed for recovery processes and it restores depleted energy levels, eliminates waste products, repairs cells
and recovers physical abilities. During SWS, a growth hormone from the pituitary gland is released and protein synthesis occurs,
which would repair cells.
Sharpio et al (1981) Runners who had taken part in an ultra marathon covering 57miles slept and hr and a half longer on the 2
nights following the marathon + much longer time devoted to SWS.
Suggests sleep is needed to repair physical exhaustion and possibly that SWS has more healing properties than other
stages. Not typical because these people are super fit.
Empson (1989) Noted that disruption of sleep in healthy people resulted in stiffness in back and muscle pain.
Supports Oswald as it suggests that SWS can cause physical problems as well as heal them.
Ryback and Lewis (1941) Healthy individuals who spent 6 weeks resting in bed showed no changes in their sleeping patterns.
Challenges Oswald as there's no psychological strain, lack of physical activity means that stage 4 sleep would be
reduced, but there was no change.
Horne (1988) Sleep as an aid to psychological recovery
Said sleep is not necessary for physical recovery, just rest without sleep. Instead, he said sleep was needed for psychological
recovery he distinguished between core sleep (SWS and REM sleep) and optional sleep (stages 13 sleep). He argued that core
sleep is critical for normal brain functioning because during it the brain restores itself after the activities of the day.
Horne and Minard (1985) exhausted their Pps with numerous activities (both mental and physical) and found people went to sleep
faster but not longer.
This doesn't support either theory as according to both, their stages of sleep would have lasted longer, but they didn't.
Sterne and Morgane (1974) REM sleep restores levels of neurotransmitters after the day's mental activities. People on
antidepressants have less REM sleep, because the drugs increase their levels of neurotransmitters, so they do not need restoring
Supports Horne's theory as core sleep (REM) is critical for normal brain functioning, but if they already have in excess they
don't need restoring therefore REM sleep is less important drugs are replacing the need for REM sleep.
Study Oswald's theory Horne's theory
Peter Tripp Physical damage to his brain was irreversible. Couldn't be repaired psychologically and it
Could perform normally although he got cold damaged his mood.
Randy Gardner Supports: made a full recovery from blurred vision Recovered from paranoia and disorganised
and paranoia. speech.
Lugaressi et al Eventually died as a result of exhaustion and He could have only stayed in the 1st 3 stages of
lack of sleep because of damage to his brain sleep and could not prepare psychologically.
Rechtschaffen et al The rat who didn't sleep died from not being able Psychologically worn from being kept awake
Jouvet Didn't recover from the deprivation and had stage Deprived of REM sleep
Webb and Bonnet Can just be using stages 4 + 5 of sleep due to
slow reduction of sleep. Supports both.
Meddis (1975) sleep and predators/ food
Species sleep for different amounts of time, he explained this by considering an animal's need for food and its method of obtaining
it and its exposure to predators. Animals that cannot find a safe place to sleep, have high metabolic rates (need more food) and/or
are at risk of predators don't sleep much.
Short tailed shrews (burrow, high M rates) have 2 hrs sleep & prey animals sleep like sheep or deer sleep 34 hrs
Lions (no predators) sleep a lot
Ground squirrel (burrow and slow metabolic rate) 14hrs
Webb (1982) Hibernation Theory
Sleep plays an evolutional role because it conserves energy. Not conserving energy may decrease chances of survival. Sleeping
when it is dark increases survival by decreasing risk of predation and death by accidents.
How long animals sleep only fits Meddis' theory, doesn't prove it.
Bottle nosed dolphins sleeps one hemisphere at a time, swaps after 3060 minutes. Ties in with Webb's theory because
one half of the dolphin's brain is conserving energy while sleeping.
Theories contradict each other: Meddis says it's only sensible to sleep when there's a safe haven Webb says sleep
decreases chances of being eaten. Meddis' theory better.
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Doesn't really apply to humans as we have no predators
The ecological theories can't explain why sleep hasn't been predated out both say sleep isn't needed, just that it prevents
things from happening. Lugaressi's study suggests that sleep itself is vital to stay alive, as does Tripp's.
Very reductionist theories: ignores psych theories with evidence to suggest its important. Suggests sleep is for
evolutionary purposes and doesn't serve any other purpose.…read more