Melatonin, a hormone produced by the pineal gland, regulates circadian rhythms. It can be derived from animals, but most melatonin is manufactured synthetically. In some countries, melatonin is considered a drug and is regulated as such.
(See also Overview of Dietary Supplements.)
Melatonin is used for the short-term regulation of sleep patterns, including jet lag and insomnia. Research into the use of melatonin supplementation for people affected by seasonal affective disorder, regulation of sleep patterns in people who work late shifts, and the resynchronization of the sleep/wake cycle in people with early Alzheimer disease is currently being evaluated.
Standard dosage is not established and ranges from 0.5 to 5 mg orally taken 1 hour before usual bedtime on the day of travel and 2 to 4 nights after arrival.
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 (1-2).
A meta-analysis of 19 studies (1683 subjects) found that in children and adults melatonin for treatment of primary sleep disorders decreases time to fall asleep by 7 minutes, increases overall sleep time by 8 minutes, and improves sleep quality (3). One meta-analysis of randomized controlled studies has provided evidence that melatonin decreases sleep onset latency in primary insomnia, benefits patients with delayed sleep phase syndrome, and helps regulate sleep-wake patterns in blind patients (4). Another meta-analysis found that melatonin provides benefit for secondary sleep disorders (secondary insomnia caused by sleep restriction)—specifically it reduces sleep onset latency and increases total sleep time, although it does not improve sleep efficiency (5). Evidence supporting use of melatonin as a sleep aid in adults and children with neuropsychiatric disorders (eg, pervasive developmental disorders) is less strong. However, in 19 randomized controlled studies, melatonin significantly improved sleep onset latency, sleep duration, and wake time after sleep onset in children with neurodevelopmental disorders (6).
Melatonin for jet lag. Drug Ther Bull 58(2):21-24, 2020. doi: 10.1136/dtb.2019.000074. Epub 2020 Jan 13.
Buscemi N, Vandermeer B, Pandya R, et al: Melatonin for Treatment of Sleep Disorders. AHRQ Publication No.
Ferracioli-Oda E, Qawasmi A, Bloch MH: Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One 8(5):e63773, 2013. doi: 10.1371/journal.pone.0063773.
Auld F, Maschauer EL, Morrison I, et al: Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders. Sleep Med Rev 34:10-22, 2017. doi: 10.1016/j.smrv.2016.06.005.
Li T, Jiang S, Han M, et al: Exogenous melatonin as a treatment for secondary sleep disorders: a systematic review and meta-analysis. Front Neuroendocrinol 52:22-28, 2019. doi: 10.1016/j.yfrne.2018.06.004.
McDonagh MS, Holmes R, Hsu F: Pharmacologic treatments for sleep disorders in children: a systematic review. J Child Neurol 34(5):237-247, 2019. doi: 10.1177/0883073818821030.
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health (NIH), National Center for Complementary and Integrative Health: General information on the use of melatonin as a dietary supplement