Describe and evaluate one theory of the function of sleep - (25 marks)
The exact function of sleep is unknown to us, and it could be possible that there is no function of sleep anymore and some people live off 2 hours or less of sleep a night. However other sleep deprivation studies have proven otherwise.
One theory of sleep is the restoration theory which entails the idea that sleeping helps us reverse and/or restore biochemical and/or physiological processes that are progessively degraded during the day. In essence, it is suggested that being awake disrupts the homeostatis of the body in some way and sleep is required to restore it. Oswald (1980) suggested that:
- REM sleep helps the brain to recover, hence the high levels of brain activity during REM sleep
- Slow wave sleep helps with body repair. There are increased levels of growth hormone during SWS
Many restorative processes, like digestion and photosynthesis, occur during sleep (Adams, 1980). However, many of these processes occur whilst awake aswell. Horne (1988) concluded that sleep does not provide any repair processes in humans, except in the brain. He also said that core sleeps function is for repair, and other sleep is optional sleep only serves the purpose of protection. Hartmann (1973) found that during sleep, adrenaline and noradrenaline is able to compensate for how much is used throughout the day by synthesising.
Some research studies have been conducted to prove Oswald's theories. Dement and Johnson (1966) studied the effects that sleep deprivation had a young boy who entered a science fair and aimed to beat the world record for hours spent without sleeping. Gardener stayed awake for 264 hours and 12 minutes. Whilst the process of sleep deprivation was in place, Gardener did suffer some irratabililty, speech difficulty, ataxia, and hallucanations. However, after he ended the wakeful period with a 14 hour sleep, it did not take him long to return to his normal 8 hour sleep regime. There were 67 hours of sleep unaccounted for, he made up for small percentages of his stage 1 and 2 sleep but made up for 68% of his stage 4 sleep and 52& of his REM sleep, showing the importance of these two stages of sleep. The process of REM sleep being made up is called 'REM rebound'.
Dement also done a study in 1960 involving 8 volunteers who spent a week in a sleep laboratory being deprived of REM sleep. Whenever the participants EEG and eye movements indicated they were…