Melatonin
Summary
In pooled trials, melatonin helped people fall asleep about 7 minutes faster and sleep about 8 minutes longer, with modestly better sleep quality. Effects grew with amounts up to about 4 mg and with earlier timing. Evidence is stronger for shifting sleep timing, as after eastward flights, than for long-term sleeplessness in adults. Label accuracy is poor, especially for gummies.
Key facts
- Fast-release tablets and capsules, slow- or prolonged-release tablets, liquids and gummies; most supplements are synthetic[1][6]
- For jet lag, 2 mg slow-release melatonin was relatively ineffective compared with fast-release doses, suggesting a short, higher peak works better (systematic review)[6]
- Sleep onset, total sleep and sleep quality improved modestly (B); earlier sleep onset with a delayed body clock (B); dose-response peaking near 4 mg/day (B); long-term sleeplessness in adults: not significant in a 2022 meta-analysis[2][4][3][5]
- Melatonin content ranged from -83% to +478% of the label in one analysis, and 26% of products contained serotonin; 22 of 25 gummy products were mislabeled in a 2023 study[7][1]
- 3 graded human outcomes on this page
- October 9, 2026
How it works
EstablishedThe brain releases melatonin in response to darkness, and it helps time circadian rhythms and sleep; light at night can block its production (established). Supplemental melatonin taken at the right time can shift the body clock, which is why timing matters for jet lag and delayed sleep timing; taken early in the day it can cause sleepiness and delay adaptation (established).[1][6]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Sleep onset and total sleep by dose and timing | Improved | Grade B | Meta-analysis · n = 1,689 · 2024 Patients with insomnia and healthy volunteers in 26 double-blind randomized controlled trials Form: melatonin · Dose: Effect rose with dose, peaking at 4 mg/day · Duration: Varied across trials Melatonin 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. | 38888087 (opens PubMed)Source [3] |
| Time to fall asleep, total sleep time and sleep quality | Improved | Grade B | Meta-analysis · n = 1,683 · 2013 People with primary sleep disorders in 19 studies comparing melatonin with placebo Form: melatonin (forms varied) · Dose: Varied; higher doses gave larger effects on sleep onset and total sleep · Duration: Varied; longer trials gave larger effects Melatonin 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. | 23691095 (opens PubMed)Source [2] |
| Earlier sleep onset with a delayed body clock | Improved | Grade B | RCT · n = 116 · 2018 Patients (mean age 29) with delayed sleep-wake phase disorder and a delayed melatonin rhythm, all following a fixed bedtime schedule Form: fast-release melatonin vs placebo · Dose: 0.5 mg 1 hour before the desired bedtime, at least 5 nights a week · Duration: 4 weeks Sleep 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. | 29912983 (opens PubMed)Source [4] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Fast-release tablets or capsules | 100%[7] | A short-lived higher peak appears to work better for jet lag than slow release (systematic review).[6] | Light-headedness, daytime sleepiness and decreased libido at rates similar to placebo in a 4-week trial.[4] | Jet lag; delayed sleep timing; sleep onset |
| Slow- or prolonged-release tablets | 100%[6] | 2 mg slow-release was relatively ineffective for jet lag in the systematic review.[6] | No form-specific tolerance data in our sources.[1] | Some insomnia trials |
| Gummies and liquids | Varies[1] | No head-to-head human data in our sources.[1] | Flavored products such as gummies feature in many accidental ingestions by young children (NCCIH, citing CDC).[1] | Not studied in the trials graded here |
Compound weight → elemental active
500 mg fast-release tablets or capsules ≈ 500 mg elemental active
Studied doses
Doses studied in human trials ranged from 0.5 to 5 mg of melatonin a night, often for a few nights (jet lag) up to 4 weeks. In a pooled analysis by amount, effects peaked near 4 mg a day.[3][4][6]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Blood thinnersNIH fact sheetPeople taking blood thinners need medical supervision when taking melatonin (NCCIH); case reports raised a possible interaction with warfarin.[1][6]
- Seizure medicines / epilepsyNIH fact sheetPeople with epilepsy need medical supervision when taking melatonin; case reports suggested possible harm.[1][6]
Who should be careful
- Children
- Talk with a health care provider first. Dose, timing and long-term effects in children are uncertain, it may affect hormonal development, and accidental ingestion of melatonin by young children has risen sharply; store it out of reach.[1]
- Pregnancy and breastfeeding
- There has been a lack of research on melatonin's safety in pregnancy and breastfeeding.[1]
- Older adults
- Melatonin may stay active longer in older people and cause daytime drowsiness. The American Academy of Sleep Medicine recommends against its use by people with dementia.[1]
- Long-term use
- Short-term use appears safe for most people, but long-term safety data are lacking. Allergic reactions are possible.[1]
- Before you start
- Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Articles about Melatonin
Plain-English answers to common questions, built on the evidence above.
Frequently asked questions
How much does melatonin help sleep?
Modestly. A meta-analysis of 19 studies found people fell asleep about 7 minutes faster and slept about 8 minutes longer, with slightly better sleep quality. A 2022 meta-analysis found no significant benefit for adults with long-term sleeplessness.[2][5]
What dose was studied?
Most trials used 0.5–5 mg. A dose-response meta-analysis found effects peaked near 4 mg a day, and a jet-lag review found doses above 5 mg no more effective.[3][6]
When should melatonin be taken?
Timing matters. For jet lag, trials gave it close to the target bedtime at the destination; taken early in the day it can cause sleepiness and delay adaptation. A dose-response analysis found larger effects when taken about 3 hours before bedtime.[6][3]
Does melatonin help jet lag?
Nine of ten trials in a systematic review found melatonin taken near bedtime at the destination reduced jet lag after crossing five or more time zones, with more benefit for eastward flights. NCCIH summarizes the evidence as suggesting it may help.[6][1]
Are melatonin labels accurate?
Often not. One study found content from 83% below to 478% above the label, with serotonin in 26% of products, and a 2023 study found 22 of 25 gummy products mislabeled.[7][1]
Is melatonin safe for kids?
NCCIH advises talking to a health care provider first. There are uncertainties about dose, timing and long-term effects, and poison-control reports involving children rose from 8,337 in 2012 to 52,563 in 2021.[1]
Sources
- [1]Melatonin: What You Need To Know. NIH National Center for Complementary and Integrative Health, 2024. fact-sheet
- [2]Meta-analysis: melatonin for the treatment of primary sleep disorders.. PLoS One, 2013. meta-analysis
- [3]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. meta-analysis
- [4]Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder: A double-blind, randomised clinical trial.. PLoS Med, 2018. RCT
- [5]Efficacy of melatonin for chronic insomnia: Systematic reviews and meta-analyses.. Sleep Med Rev, 2022. meta-analysis
- [6]Melatonin for preventing and treating jet lag.. Cochrane Database Syst Rev, 2001. systematic-review
- [7]Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content.. J Clin Sleep Med, 2017. observational
What changed
- First draft. Every evidence-row PMID checked with NCBI E-utilities (esummary + efetch abstract) and re-read in an independent adversarial pass.
- Added cost-per-studied-dose method, labeled analysis derived from cited rows.