Overview:

Melatonin is a hormone secreted by the pineal gland in the brain. It helps regulate other hormones and maintains the body's circadian rhythm. The circadian rhythm is an internal 24-hour clock that plays a role in when we fall asleep and when we wake up. When it is dark, your body produces more melatonin, especially during dreamtime; when it is light, the production of melatonin drops.

The more you're exposed to Light during the day, the more Melatonin you produce during the night.

Researchers also believe that melatonin levels may be related to aging. For example, young children have the highest levels of nighttime melatonin.