Functions of Sleep

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Functions of Sleep

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Sleep serves an important function as we spend about one third or our

lives asleep. Theories of why we sleep can be separated into two

explanations Restorative theories, and Ecological theories.

The restoration theory claims that sleep enables the body to make

repairs after the exertions of the day. Evidence for the role of SWS

comes for the hypothesis that if SWS serves the purpose of repairing

the body then physical exercise should lead to more SWS.

Shapiro et al. (1981) studied the sleep patterns of long distance

runners. After a 57 mile race they found that the runners slept 1.5

hours longer than normal on the 2 nights following the race. In

particular, there was an especially large increase in the amount of

time devoted to SWS. However, Horne & Minard (1985) did a more

controlled lab study and found that sleep length was not affected by a

series of exhausting cognitive & physical activities. The participants

went to sleep more quickly but with no increase in sleep duration.

Further evidence for restoration theory comes from total sleep

deprivation studies. Instead of targeting either REM or SWS these

studies involve the participant not sleeping for as long as possible.

Participants were volunteers and it was also a small sample.

Therefore, the findings of the research cannot be generalised to the

wider population.

Oswald observed patients recovering from injuries to their central

nervous system. He found an increase in the quantity of REM sleep

which suggests that there was a recovery process going on in the

brain. There is also a correlation in the quantity of REM sleep and

brain weight increase in newborn babies, their rapid brain growth is

due to their long REM sleep.

The restoration perspective also states that sleeping is a way of

conserving and making important neurotransmitters. These are important

to our alertness during the day as it helps the transmission of nerve

impulses. As time passes during the day, neurotransmitter levels fall.

During REM sleep neurons synthesise new neurotransmitters for release

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