Melatonin, a hormone produced by the pineal gland, regulates circadian rhythms. It is derived from animals or can be manufactured synthetically. In some countries, melatonin is considered a drug and is regulated as such.
Some scientific evidence supports use of melatonin to minimize the effects of jet lag, especially in people traveling eastward over 2 to 5 time zones. (See the Cochrane review's abstract Melatonin for the Prevention and Treatment of Jet Lag and the Agency for Healthcare Research and Quality EPC Evidence Report Melatonin for Treatment of Sleep Disorders.) However, in one large well-designed study, melatonin supplements did not relieve symptoms of jet lag, and only a few small studies suggest that these supplements can treat insomnia.
Standard dosage is not established and ranges from 0.5 to 5 mg po taken 1 h before usual bedtime on the day of travel and 2 to 4 nights after arrival. Evidence supporting use of melatonin as a sleep aid in adults and children with neuropsychiatric disorders (eg, pervasive developmental disorders) is less strong.
Hangover drowsiness, headache, and transient depression may occur. Melatonin may worsen depression. Theoretically, prion infection caused by products derived from neurologic tissues of animals is a risk.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified November 2012