Over 27 million American adults took melatonin in the past year, making it the top-selling sleep supplement by a wide margin. Dr. Richard Wurtman, professor of neuroscience at MIT and the researcher who first identified melatonin's role as a chronobiotic signal in the 1990s, has spent three decades arguing that commercial doses are ten to thirty times higher than the body needs. Most consumers are taking too much, too late, and for the wrong indication. Understanding melatonin as a chronobiotic rather than a sedative reframes its proper use.
Melatonin is not a sleeping pill. It signals darkness to the brain. It is most effective for circadian misalignment — jet lag, shift work, delayed sleep-wake phase disorder — and less effective for general insomnia. A PLoS ONE meta-analysis (k=19, n=1,683) by Dr. Eduardo Ferracioli-Oda at Yale found melatonin reduces sleep onset latency by 7.06 minutes in primary insomnia, with stronger effects for delayed sleep phase (onset latency reduced by 22-34 minutes).
Dosing: physiological production corresponds to approximately 0.3-0.5 mg. Most commercial products contain 3-10 mg. Higher doses are not more effective and may cause morning grogginess through receptor desensitization. Start with 0.3-0.5 mg.
Timing matters more than dose. Take melatonin 1-2 hours before desired bedtime, not at bedtime. For eastward jet lag, take at destination bedtime starting the day of travel.
Quality concerns: a 2017 study by Dr. Lauren Erland and Dr. Praveen Saxena at the University of Guelph, published in the Journal of Clinical Sleep Medicine, tested 31 supplements and found actual content ranged from 83% less to 478% more than labeled. Additionally, 26% of products contained serotonin as a contaminant. Third-party testing through NSF or USP is essential.
For children: Dr. Judith Owens, professor of neurology at Harvard Medical School and director of the Center for Pediatric Sleep Disorders at Boston Children's Hospital, notes that the AAP does not recommend routine use in healthy children. Melatonin has a role in neurodevelopmental disorders — particularly autism spectrum disorder and ADHD — where circadian disruption is documented. A Developmental Medicine and Child Neurology review (k=13, n=795) confirmed efficacy in these populations, but long-term effects on pubertal development remain unstudied.
Dr. Alfred Lewy, a psychiatrist at Oregon Health and Science University who pioneered melatonin research in the 1980s, demonstrated that the dose-response curve for melatonin is not linear — doses above 1 mg can actually desensitize melatonin receptors and reduce effectiveness over time. His work established that 0.3 mg produces plasma levels closest to the body's natural nocturnal peak of 60-70 pg/mL.
Extended-release formulations address a different problem: difficulty maintaining sleep. Standard melatonin has a half-life of only 20-40 minutes. For individuals who fall asleep easily but wake at 2-3 AM, an extended-release formulation at 0.3-1 mg may be more appropriate than a higher dose of immediate-release. A 2014 Neurology trial (n=240) by Dr. Nir Giladi at Tel Aviv University found that extended-release melatonin at 2 mg improved sleep quality in patients over 55 without next-day impairment — one of the few studies supporting a higher dose in a specific population.