Sleep is natural to all people and animals. Evidence has recently been discovered to prove that even sharks sleep, something formerly disbelieved.

For centuries it was thought that sleep was necessary to restore physical well being. This reasoning was questioned when it was seen how much the body moves during sleep. . It was thought that the brain 'switched off' during sleep. However it was later discovered that the brain was actually a more active during sleep and sleep deprivation caused mental disturbance and disorientation.

Some years ago an American disc jockey called Peter Tripp decided to stay awake for 200 hours to raise money for charity. His sleep became slurred, and then incoherent, and he became paranoid.

Lack of sleep clearly harms the body and the mind

REM and NREM

There are two types of sleep which can be distinguished between by EEG (electroencephalogram) readings.

The first is termed Rapid Eye Movement sleep (REM) where the eyes dart rapidly back and forth. It is during this stage that it is believed that one dreams. The more active the dream, the more rapid the eye movements. The pulse speeds up, and the blood pressure and respiration become irregular. Usually REM sleep lasts about twenty minutes and there are four or five episodes during sleep. REM is thought to be when the brain and nervous systems restore themselves.

NREM takes up to 80% of sleep time. There seems to be an outpouring of growth hormone from the pituitary gland. This is thought to promote repair and restoration of bodily functions It was believed that no dreaming occurs. However recently it has been discovered that subject awoken during NREM thought they were dreaming...

The Function of Dreams

Some neurophysiologists contend that dreams occur as a sort of discharge of mental activity necessary for brain repair, Others argue the opposite and that dreaming is important for the mind and brain. Sleep deprivation has been shown to develop anxiety states and other emotional problems.

Dreams can be viewed as extension of waking life which include thoughts and concerns especially emotional ones. In a sense dreams provide clues to the person's problems, concerns and emotions (Plotnik 1993).

There are still a lot of unanswered questions about the reasons for sleep and dreams.

Clearly far more research needs to be done.