Melatonin is a hormone produced by the pineal gland, a small gland in the brain. Melatonin helps control their sleep-wake cycles. Very small amounts of melatonin which are found in foods such as meat, grains, fruits and vegetables. You can also buy as a supplement of melatonin for those who suffer from disorders of the sleep cycles.
Your body has its own internal clock that controls the natural cycle of sleep and waking hours. In part, his biological clock controls the amount of melatonin produced by your body.
Normally, the melatonin levels begin to increase to mid-to-late afternoon, remain high for most of the night, and then fall in the early hours of the morning.