Melatonin
HormoneAlso known as: N-acetyl-5-methoxytryptamine
A pineal hormone that regulates circadian rhythm and sleep timing. Most experts recommend much lower doses (0.1–0.5mg) than typical OTC products (5–10mg). Best evidence for jet lag and circadian phase shifts.
The bottom line
Melatonin is best understood as a circadian-timing signal, not a sleeping pill — its most legitimate uses are jet lag and shifting your body clock, and even Huberman and Tracey Marks (both tracked here) urge caution about routine use. The broad sleep claims outrun the evidence. Two practical points: a low dose (0.5–3 mg) is usually all that's needed, and product dose-accuracy is notoriously poor, so a third-party-tested product matters (see the sourcing checklist). Avoid in pregnancy and in children without medical guidance.
Our plain-language reading of the expert claims and research on this page. Not medical advice.
How expert claims hold up
216 of 216 claims assessed9 of 216 assessed claims supported or partially supported by published research
Expert Consensus
Dose divergence: Experts recommend different amounts (5-10milligrams, 10milligrams, 0.5-1milligram, 0.1-0.3milligrams, 5–10milligrams, 0.5milligrams, 0.3milligrams, 0.1–0.5milligrams, 0.1–0.3milligrams). Check the Stack & Timing tab for study-backed dosing ranges.
Evidence Summary
The available research on melatonin paints a consistent picture of it as a hormone with well-characterized biological roles, though the evidence base for many specific health claims remains limited or indirect. Across multiple reviews and meta-analyses, melatonin is reliably described as a chronobiotic agent — a darkness-signaling hormone produced by the pineal gland — rather than a sedative or sleeping pill. This mechanistic characterization is one of the most consistently supported findings in the literature reviewed. Beyond its role in circadian regulation, melatonin has been studied in contexts ranging from fertility and ICU care to cardiovascular health and traumatic brain injury, suggesting broad biological relevance, though the strength of evidence varies considerably across these applications. The strongest evidence clusters around melatonin's role in sleep quality improvement and its use in ICU settings, supported by systematic reviews and meta-analyses, which represent the highest tier of study design. A meta-analysis on dietary supplements and sleep quality found melatonin among the agents with measurable effects on sleep outcomes. Separately, a systematic review and meta-analysis on ICU use provides moderate-to-strong support for melatonin's application in that specialized population. Reviews touching on fertility, PCOS, and antioxidant supplementation mention melatonin as a candidate intervention, but findings in these areas are more preliminary and less conclusive. The majority of expert-level claims evaluated — 199 out of 214 — were rated as having insufficient evidence, which underscores how much of the popular discourse around melatonin outpaces the current science. Several important caveats limit confidence in the broader evidence base. Most studies reviewed are narrative or general reviews rather than large, high-quality RCTs with melatonin as the primary intervention. Populations studied are often not clearly defined, making it difficult to generalize findings. Pediatric use is a particular area of concern: one review specifically addresses pharmacotherapy in children with neurodevelopmental disorders, and the available literature supports caution rather than routine use in this group, citing limited long-term safety data. Dosing, timing, and formulation vary widely across studies, and long-term effects of supplementation remain poorly characterized. The gap between what is scientifically established and what is widely claimed about melatonin is substantial.
Read full evidence summary →Top studies
Antioxidants and Fertility in Women with Ovarian Aging: A Systematic Review and Meta-Analysis.
Antioxidants and Fertility in Women with Ovarian Aging: A Systematic Review and Meta-Analysis.
Antioxidants for female subfertility.
Antioxidants for female subfertility.
Expert Mentions
All 216 mentions
“Some animal studies suggest it may affect pubertal timing, though this hasn't been demonstrated in humans definitively.”
Some animal studies suggest melatonin supplementation may affect pubertal timing, though this has not been definitively demonstrated in humans.
None of the 10 provided studies directly address the claim that melatonin supplementation may affect pubertal timing in animals or humans. The retrieved literature covers topics such as sleep quality,…
“I'm particularly cautious about melatonin in children and teenagers. There's limited long-term safety data, and melatonin plays developmental roles that we don't fully understand.”
Huberman is particularly cautious about melatonin use in children and teenagers due to limited long-term safety data and melatonin's developmental roles that are not fully understood.
None of the 10 provided studies directly address melatonin safety in children or adolescents, or melatonin's developmental roles. The retrieved literature covers topics such as melatonin in ICU patien…
Safety, interactions & who should avoid Melatonin
generally_recognized_safe
Melatonin is generally described as well-tolerated in short-term adult use across the reviewed literature, but long-term safety data are limited and caution is specifically warranted in children and adolescents due to melatonin's hormonal nature and insufficient pediatric safety evidence.
Melatonin is generally considered safe for short-term use in adults, but long-term effects remain understudied. High OTC doses (5–10 mg) far exceed physiological levels and may desensitize melatonin receptors over time. Pediatric use should occur only under medical supervision at the lowest effective dose for the shortest necessary duration. Users should always disclose melatonin use to their healthcare provider, particularly given potential interactions with medications.
Who should avoid it
Individuals who are pregnant or breastfeeding should use caution due to insufficient safety data. Those with autoimmune conditions should consult a physician given melatonin's immunomodulatory activity. Children and adolescents should only use melatonin under medical guidance. People with bleeding disorders or taking anticoagulants should exercise caution.
Known interactions
- ·Anticoagulants (e.g., warfarin) — melatonin may enhance anticoagulant effects
- ·CNS depressants and sedatives — additive sedation risk
- ·Immunosuppressants — melatonin has immunomodulatory properties that may interfere
- ·Antidiabetic medications — melatonin may affect insulin sensitivity and glucose regulation
- ·Hormonal contraceptives — may alter melatonin metabolism or endogenous levels
Pregnancy & breastfeeding
Our sources specifically flag pregnancy or breastfeeding considerations for Melatonin — see the cautions above.
We don’t assign pregnancy-safety ratings. Many supplements lack adequate safety data in pregnancy and breastfeeding, and the absence of a warning here does not mean a supplement is safe to take. Don’t start, stop, or continue any supplement while pregnant or nursing without your OB-GYN or midwife.
Read: Supplements during pregnancy & breastfeeding →This is educational information only. Consult a healthcare provider before starting any supplement.
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Sourcing matters for Melatonin
The poster child for dose-accuracy failure — independent testing found products ranging from a fraction to several times the labeled dose, with some containing serotonin.
What to check before you buy
- ✓Third-party tested for actual content vs. label (USP Verified is the gold standard)
- ✓Tested to be free of serotonin and other contaminants
- ✓A low dose available (0.5–3 mg; many products overdose at 5–10 mg)
- ✓Exact mg labeled — no proprietary "sleep blend" hiding the melatonin amount
This is about product quality — separate from the evidence grade above, which scores the research. Our sourcing standards →
No buy link — yet
We only link products that meet our sourcing standards — use the checklist above if you’re shopping on your own. We haven’t linked one for Melatonin yet. Our standards →
Key findings
- ·Melatonin is consistently characterized across multiple reviews as a chronobiotic hormone — a darkness signal produced by the pineal gland — not a sedative or sleep drug.
- ·A meta-analysis on dietary supplements found melatonin associated with improvements in sleep quality outcomes, representing one of the stronger evidence-based applications.
- ·A systematic review and meta-analysis supports melatonin use in ICU patients, suggesting potential benefits in this specific clinical population.
Evidence gaps
- ·Long-term safety and efficacy data for melatonin supplementation in healthy adults and children are largely absent from the reviewed literature, leaving many dosing and duration questions unanswered.
- ·Most reviewed studies are narrative reviews or general overviews rather than large, well-controlled RCTs, making it difficult to establish causality or optimal dosing protocols for specific conditions.
- ·Evidence for melatonin in specialized areas such as fertility, PCOS, cardiovascular health, and traumatic brain injury is indirect or preliminary, based on reviews that include melatonin among many interventions rather than dedicated melatonin trials.