Evidence explainerMelatonin
How Much Melatonin Should You Take? Trials Used 0.5 to 5 mg, and Timing Mattered as Much as Dose
Store shelves run up to 10 mg and beyond, but most trials used far less. A 2024 dose-response analysis also found that when you take it changes how well it works.
Key takeaways
- Most trials used 0.5 to 5 mg; a 2024 dose-response meta-analysis found effects peaked near 4 mg a day [2][3].
- Effects were larger when melatonin was taken about 3 hours before bedtime than the common 2 mg 30 minutes before [2].
- Across 19 studies, melatonin helped people fall asleep about 7 minutes faster and sleep about 8 minutes longer [4].
- In people with a delayed body clock, 0.5 mg taken 1 hour before the desired bedtime moved sleep 34 minutes earlier [5].
- Short-term use appears safe for most people; long-term safety data are lacking [1].
The evidence, graded
Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.
- Grade BImprovedSleep onset and total sleep by dose and timingMelatonin gradually reduced sleep onset latency and increased total sleep time, peaking at 4 mg/day. Effects were larger in people with insomnia and when taken earlier before bedtime (about 3 hours) than the common 2 mg 30 minutes before.
- Grade BImprovedTime to fall asleep, total sleep time and sleep qualityMelatonin shortened sleep onset by about 7 minutes, increased total sleep by about 8 minutes and modestly improved sleep quality (SMD 0.22) versus placebo. Effects did not fade with continued use.
- Grade BImprovedEarlier sleep onset with a delayed body clockSleep began 34 minutes earlier with melatonin than placebo; sleep disturbance, insomnia severity and functional disability scores fell, and more patients improved (52.8% vs 24.0%). Side-effect rates were similar between groups.
How much it helps
A 2013 meta-analysis of 19 studies (1,683 people with primary sleep disorders) found melatonin cut the time to fall asleep by about 7 minutes and added about 8 minutes of sleep, with a modest gain in sleep quality [4]. The effects did not fade with continued use [4].
For long-term sleeplessness in adults, guidelines from the American Academy of Sleep Medicine and the American College of Physicians found the evidence too weak to recommend melatonin [1].
The dose: more is not better past about 4 mg
A 2024 meta-analysis of 26 double-blind trials found the effect on sleep onset and total sleep rose with dose and peaked at 4 mg a day [2]. In a jet-lag review, doses above 5 mg were no more effective than lower ones [3].
Labels are a separate problem. NCCIH reports a 2023 study in which 22 of 25 melatonin gummy products were mislabeled, with content from 74% to 347% of the label [1]. A pill marked 3 mg may not contain 3 mg; we cover that in melatonin gummies and kids.
The timing: earlier than most people take it
The same 2024 analysis found larger effects when melatonin was taken about 3 hours before bedtime, compared with the common habit of 2 mg 30 minutes before [2]. Effects were also larger in people with insomnia than in healthy volunteers [2].
For a delayed body clock, a 2018 trial gave 0.5 mg of fast-release melatonin 1 hour before the desired bedtime, at least 5 nights a week, alongside a fixed sleep schedule [5]. Sleep began 34 minutes earlier than with placebo, and 52.8% improved versus 24.0% [5].
Jet lag
In a systematic review, 9 of 10 trials found melatonin taken close to the target bedtime at the destination reduced jet lag after crossing five or more time zones, especially on eastward flights [3]. Taken at the wrong time of day, it can cause sleepiness and delay adaptation [3]. NCCIH summarizes the evidence as suggesting melatonin may help [1].
Who should be careful
NCCIH flags these groups for extra care with melatonin:
- Older adults: melatonin may stay active longer and cause daytime drowsiness, and the American Academy of Sleep Medicine recommends against its use in people with dementia [1].
- People with epilepsy or on blood thinners: use it only under medical supervision [1].
- Pregnancy and breastfeeding: there has been a lack of research on safety [1].
- Children: talk with a health care provider first [1].
Quick answers
Is 10 mg of melatonin too much?
Trials mostly used 0.5 to 5 mg, effects peaked near 4 mg a day, and doses above 5 mg were no more effective for jet lag [2][3]. Long-term safety at any dose is not well studied [1].
How long before bed should I take melatonin?
A 2024 meta-analysis found larger effects about 3 hours before bedtime than 30 minutes before [2]. For jet lag, trials gave it near bedtime at the destination [3].
Can you take melatonin every night?
Short-term use appears safe for most people, but long-term safety data are lacking [1].
Keep reading
Full monographs
Related articles
- Melatonin Gummies: 22 of 25 Were Mislabeled, and Child Poison-Center Calls Rose Sixfold
- Ashwagandha for Stress and Sleep: What the Trials Found, and Why the Results Vary So Much
- Ashwagandha Side Effects: The Liver, Thyroid and Pregnancy Warnings Behind Denmark’s Ban
- How Much Magnesium Is Too Much? The 350 mg Rule, the Label Trap and Who Should Be Careful
Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.
References
- [1]Melatonin: What You Need To Know. NIH National Center for Complementary and Integrative Health, 2024.
- [2]Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. J Pineal Res, 2024.
- [3]Melatonin for preventing and treating jet lag. Cochrane Database Syst Rev, 2001.
- [4]Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One, 2013.
- [5]Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder: A double-blind, randomised clinical trial. PLoS Med, 2018.