Melatonin is a neurohormone produced in humans by the pineal gland. A favorite of travelers, it governs the body's circadian rhythms, helping the body ease into restful sleep. Melatonin is also a potent antioxidant. Source Naturals Timed-Release Melatonin is formulated to allow for a gradual release of the active ingredient during an approximate six hour period. This provides the body with a more even absorption of melatonin.