The physiology of sleep

The brain stem has a role in key functions such as alertness but it also controls sleep. The suprachiasmatic nucleus reacts to light, stimulating melatonin production from the pineal gland, causing the release of seretonin and allowing reticular activating system activity to lessen, bringing the onset of sleep. The release of noradrenaline causes the onset of REM sleep and the hormone acetycholine is involved with brain activation during wakefulness and sleep.

• Dement and Kleitman (1957) found that sleep consits of a sequential series of five stages, each with different characteristics, occuring in…