Since its discovery, the pineal hormone melatonin has been shown to have consistent sleep-promoting effects when ingested throughout the diurnal day.
Endogenous melatonin is produced primarily at night in dim light.
In individuals on normal sleep-wake schedules, melatonin levels begin to rise approximately two hours prior to sleep, remain elevated throughout the night, and begin to decline prior to the termination of sleep. Melatonin can also facilitate the initiation of sleep, even at doses that produce plasma levels equivalent to nighttime levels. In spite of these hypnotic-like effects, melatonin does not cause significant anterograde amnesia or other memory impairment either immediately after administration or the next day. Melatonin may be less potent but more safe than currently prescribed hypnotics. Top of page Clinical Applications of Melatonin Preliminary evidence suggests that melatonin may be useful for treating individuals with sleep-schedule and circadian sleep disorders.