Melatonin

Melatonin is a hormone your body makes naturally that helps regulate the sleep-wake cycle. It signals timing ("it's night now") more than it acts as a sedative. That's why the evidence is strongest where the problem is timing, like jet lag, and weaker for insomnia in general.

Use has grown quickly. In national survey data covering 55,021 U.S. adults, melatonin use rose from 0.4% in 1999–2000 to 2.1% in 2017–2018, and use above 5 mg/day (not reported before 2005–2006) also increased.

Read the study (Li et al., JAMA, 2022) →

Insomnia and falling asleep (modest): a meta-analysis of 19 placebo-controlled trials (1,683 people with primary sleep disorders) found melatonin helped people fall asleep about 7 minutes faster and sleep about 8 minutes longer, with a small improvement in sleep quality. The authors called the effects "modest" and noted they're smaller than those of prescription insomnia drugs, but that the benefit didn't fade with continued use.

Read the meta-analysis (Ferracioli-Oda et al., PLoS One, 2013) →

Separately, the American Academy of Sleep Medicine's 2017 guideline suggests that clinicians not use melatonin to treat chronic sleep-onset or sleep-maintenance insomnia in adults. That's a "weak" recommendation, which the guideline says reflects lower certainty and "should not be construed as an indication of ineffectiveness."

Read the AASM guideline (Sateia et al., Journal of Clinical Sleep Medicine, 2017) →

Jet lag (stronger): a Cochrane review found that in 9 of 10 trials, melatonin taken close to the target bedtime at the destination reduced jet lag from flights crossing five or more time zones. Benefits were likely greater the more time zones crossed, and smaller for westward flights. Note that it's an older review (2002).

Read the Cochrane review (Herxheimer & Petrie, 2002) →

In the U.S., melatonin is regulated by the FDA as a dietary supplement and widely sold over the counter. In the UK, the NHS lists melatonin as prescription-only, mainly for short-term sleep problems in people aged 55 and over.

Label accuracy is a documented problem, and what's in the bottle can differ a lot from the label. A 2017 analysis of 31 melatonin supplements found actual content ranged from 83% below to 478% above the labeled amount. More than 71% weren't within 10% of their label, and 26% contained serotonin. A 2023 analysis of 25 U.S. melatonin gummy products found they contained 74% to 347% of the labeled melatonin, and only 3 were within ±10% of the label.

Read the supplement analysis (Erland & Saxena, Journal of Clinical Sleep Medicine, 2017) →

Read the gummy analysis (Cohen et al., JAMA, 2023) →

There's no official U.S. dosing standard for over-the-counter melatonin. For jet lag, the Cochrane review found daily doses between 0.5 and 5 mg similarly effective, except that people fell asleep faster and slept better on 5 mg than 0.5 mg. Doses above 5 mg appeared no more effective. Timing mattered more than dose. It worked when taken close to the target bedtime at the destination, and taking it early in the day could cause daytime sleepiness and delay adjusting to local time. Given the label-accuracy findings above, the amount you actually get may differ from the number on the label. Source: Cochrane review above.

Children: per the CDC's MMWR, pediatric melatonin ingestions reported to U.S. poison control centers rose 530% from 2012 to 2021. Most of the rise in serious outcomes came from unintentional ingestions by children aged 5 and under, and hospitalizations increased too. Keep melatonin, especially gummies, out of reach. Talk to a pediatrician before giving it to a child, since the gummy study above found doses could be unpredictable.

Read the CDC report (Lelak et al., MMWR, 2022) →

Epilepsy and warfarin: the Cochrane review noted case reports suggesting people with epilepsy and people taking warfarin may come to harm from melatonin, so check with your doctor first. Otherwise, the review found side effects uncommon and occasional short-term use appeared safe.

If the real issue is sleep timing rather than falling asleep, our Sleep Cycle Calculator can help you pick a bedtime or wake-up time that lines up with full sleep cycles.