Supplement evidence
Melatonin
The sleep evidence, and how much melatonin is actually in the bottle.
What Its Legal Status Actually Means
Read this before anything below it. Legal to sell is not the same fact as reviewed, verified, or approved.
In the United States melatonin is sold over the counter as a dietary supplement under the Dietary Supplement Health and Education Act of 1994 (DSHEA). The FDA does not review it for safety or effectiveness before sale, does not verify that a tablet or gummy contains the dose printed on the label, and has never approved melatonin to treat insomnia or any other condition. That regulatory posture is unusual internationally: melatonin is a hormone, and in the United Kingdom and the European Union it is a prescription-only medicine, not a supplement — prolonged-release melatonin (Circadin, 2 mg) has been authorised by the European Medicines Agency since 2007 for short-term treatment of insomnia in adults aged 55 and over, and a paediatric prolonged-release formulation (Slenyto) was authorised in 2018 for insomnia in children and adolescents with autism spectrum disorder or Smith-Magenis syndrome. A British traveller cannot buy at a pharmacy what an American buys at a supermarket checkout, and the American product's actual content is not verified by anyone.
Quoted whole from the 2026-08-18 study harvest. Not summarized, not shortened.
What the Research Shows
5 records from the 2026-08-18 harvest, each checked against PubMed and Europe PMC on that date. How a study was designed, how many people were in it, and who paid for it are printed above what it found, because those three facts decide how much the finding is worth.
Study 1 · 2017
- Clinical guideline
- Reputable journal
- Independently funded
- Declared conflicts of interest
gold standard86/100Top of the evidence hierarchy, independently funded.
Read this first: All 14 recommendations in this guideline are WEAK, including the ones in favour of prescription hypnotics, and the task force explicitly notes that evidence quality is routinely downgraded because most hypnotic trials are industry-funded. So the guidance against melatonin sits in a field of uniformly thin evidence rather than reflecting a uniquely poor showing. Several task-force members disclosed industry consulting relationships and recused themselves from the corresponding drug recommendations.
After a GRADE-based systematic review of randomized trials, the American Academy of Sleep Medicine's guideline states: "We suggest that clinicians not use melatonin as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults." That is a recommendation against, in the same list that recommends against valerian, tryptophan, trazodone, and diphenhydramine. The recommendation is graded WEAK, which under GRADE reflects low certainty of the underlying evidence rather than a strong claim that melatonin is useless — but it is a recommendation not to use it.
How this record was checked
PubMed record 27998379 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, and the melatonin recommendation quoted above confirmed verbatim from the abstract's RECOMMENDATIONS section. PMC full text (PMC5263087) retrieved 2026-08-18: the Disclosure Statement reads "The development of this clinical practice guideline was funded by the American Academy of Sleep Medicine" and lists individual member conflicts and recusals, hence funding INDEPENDENT (professional society, no commercial sponsor) and conflicts true.
Study 2 · 2010
- Meta-analysis of randomized trials
- 317 participants
- Reputable journal
- No funding reported
- Declared conflicts of interest
gold standard87/100Top of the evidence hierarchy, independently funded.
Read this first: Nine small trials totalling 317 people, published in 2010, and the benefit is a shift of roughly 40 minutes to an hour in when sleep starts — real, but modest, and it delivers no extra total sleep. Effect depends heavily on taking the dose at the right time relative to one's own melatonin onset; taken at the wrong hour it can push the clock the wrong way.
Pooling 5 randomized trials in 91 adults and 4 in 226 children with delayed sleep phase disorder, melatonin advanced the body's own melatonin onset by 1.18 hours (95% CI 0.89-1.48), moved clock-time of falling asleep 0.67 hours earlier (95% CI 0.45-0.89), and cut sleep-onset latency by 23.27 minutes (95% CI 4.83-41.72). Wake-up time and total sleep time did not change significantly. This is melatonin's real job: it shifts the timing of the body clock in people whose clock is late. It does not make you sleep more.
How this record was checked
PubMed record 21120122 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, the 5 adult trials (n=91) and 4 paediatric trials (n=226), the 1.18 h endogenous melatonin onset advance, the 0.67 h sleep-onset advance, the 23.27 minute latency reduction, and the null results for wake-up time and total sleep time confirmed verbatim from the abstract. PMC full text (PMC2982730) retrieved 2026-08-18: the Disclosure Statement reads "This was not an industry supported study. The authors have indicated no financial conflicts of interest" and the Acknowledgments read "No sponsorship was received", hence funding NONE and independent true.
Study 3 · 2013
- Meta-analysis of randomized trials
- 1,683 participants
- Indexed journal
- Mixed funding
- Declared conflicts of interest
strong75/100Well-supported by good-quality research.
Read this first: The competing-interests statement records that the work was "partly funded by APIRE/Eli Lilly Psychiatric Research Fellowship" and "the AACAP/Eli Lilly Pilot Research Award" alongside NIH grants, so the funding is mixed rather than fully independent — though Eli Lilly markets no melatonin product, so there is no proponent conflict on this specific question. The pooled 7-minute and 8-minute effects are statistically significant and clinically trivial; readers who see melatonin described as "effective" are usually seeing this paper's conclusion divorced from its numbers.
Across 19 randomized placebo-controlled trials in 1,683 adults and children with primary sleep disorders, melatonin cut the time taken to fall asleep by 7.06 minutes (95% CI 4.37 to 9.75) and increased total sleep time by 8.25 minutes (95% CI 1.74 to 14.75), with a small improvement in sleep quality (standardized mean difference 0.22). Seven minutes. The authors state directly that "the absolute benefit of melatonin compared to placebo is smaller than other pharmacological treatments for insomnia."
Ferracioli-Oda E, Qawasmi A, Bloch MH. (2013). Meta-analysis: melatonin for the treatment of primary sleep disorders. PLOS ONE. PMID 23691095.
How this record was checked
PubMed record 23691095 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, the 19 studies and 1,683 subjects, sleep latency WMD 7.06 minutes (95% CI 4.37-9.75), total sleep time WMD 8.25 minutes (95% CI 1.74-14.75), and sleep quality SMD 0.22 (95% CI 0.12-0.32) confirmed verbatim from the abstract, along with the competing-interests statement naming the two Eli Lilly-supported awards. Europe PMC core record fetched 2026-08-18 additionally lists NIMH K23 MH091240 and NCRR UL1 RR024139; both statements read, hence funding MIXED.
Study 4 · 2017
- Cross-sectional study
- 31 participants
- Reputable journal
- Independently funded
- Declared conflicts of interest
moderate60/100Reasonable evidence with real limitations.
Read this first: Thirty-one samples of Canadian products bought in 2016; it does not measure how common the problem is across the whole market, and the later US gummy analysis (Cohen 2023, below) did not detect serotonin in any product it tested, so the serotonin contamination finding has not been replicated in the US supply.
Chemical analysis of 31 commercial melatonin supplement samples found actual melatonin content ranging from 83% below to 478% above the labelled amount, with lot-to-lot variation within a single product of as much as 465%; more than 71% of products missed their own label by more than a 10% margin, and the variability was unrelated to manufacturer or product type. Serotonin — a controlled substance in this context — was detected in 8 of the supplements at 1 to 75 micrograms. Someone taking "the same" melatonin nightly may be taking a fifth of the stated dose one month and five times it the next.
How this record was checked
PubMed record 27855744 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, the 31 supplements analyzed, the -83% to +478% content range, the 465% lot-to-lot variation, the ">71% missed label within a 10% margin" figure, and serotonin in 8 supplements at 1-75 micrograms confirmed verbatim from the abstract. PMC full text (PMC5263083) retrieved 2026-08-18: the Disclosure Statement reads "This work was supported by the National Sciences and Engineering Research Council (NSERC) of Canada grant number 46741. The authors have indicated no financial conflicts of interest", hence funding INDEPENDENT.
Study 5 · 2023
- Cross-sectional study
- 25 participants
- Top-tier journal
- Funding not established
- Declared conflicts of interest
early signal49/100Suggestive but preliminary. Not settled.
Read this first: The authors state their own limits: only 25 products, one sample per brand, gummies only, and no test of whether tablets and capsules behave the same or whether a given brand varies batch to batch. It measures label accuracy, not clinical harm.
Of 25 US melatonin gummy products analysed, 22 (88%) were inaccurately labelled and only 3 (12%) contained melatonin within 10% of the declared amount; measured content ranged from 74% to 347% of the label, one product labelled 3 mg contained 10.4 mg, and one product contained no detectable melatonin at all but 31.3 mg of CBD. Serotonin was not detected in any product. The authors calculate that a child taking these gummies as directed could receive 40 to 130 times the 0.1-0.3 mg needed to raise blood melatonin into the normal night-time range.
Cohen PA, Avula B, Wang YH, Katragunta K, Khan I. (2023). Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US. JAMA. PMID 37097362.
How this record was checked
PubMed record 37097362 fetched via NCBI efetch 2026-08-18 confirming title, authors, journal (JAMA), year, DOI and the conflict-of-interest disclosures. PMC full text (PMC10130950) retrieved 2026-08-18: Results confirm 25 products analysed, melatonin 74% to 347% of labelled quantity, 22 of 25 (88%) inaccurately labelled with only 3 (12%) within ±10%, one product with no detectable melatonin but 31.3 mg CBD, brand S labelled 3 mg measuring 10.4 mg (347%), CBD 104-118% of label in the 5 products declaring it, and "Serotonin was not detected in any product." No funding or support statement appears in the article, so funding is recorded UNKNOWN rather than inferred.
The Risks
Nobody checks this purchase the way a prescription is checked. No prescriber reviews it against the rest of what you take, no pharmacist screens the interaction, and no regulator confirms the dose in the capsule before it is sold. That is why this section sits here at full length rather than as a footnote.
What the paragraph below covers:
- Accidental ingestion by children
- Drug interactions
- What is actually in the product
- Sleep disruption
- Sedation
The most concrete documented risk is that the bottle is not what the label says. Independent chemical analyses have found melatonin content ranging from 83% below to 478% above the label claim, lot-to-lot variation within a single product of up to 465%, serotonin contamination in a quarter of Canadian products tested, and 88% of US melatonin gummy brands inaccurately labelled — including one product that contained no detectable melatonin at all but 31.3 mg of CBD. A "3 mg" gummy has been measured at 10.4 mg. Clinically, melatonin commonly causes next-day grogginess, headache, and daytime sleepiness, and taken at the wrong time of day it shifts the body clock in the wrong direction and makes matters worse. Paediatric exposure has become a real public-health problem: US poison centres logged 260,435 paediatric melatonin ingestions from 2012 to 2021 with the annual number rising 530%; melatonin accounted for 4.9% of all paediatric poison-centre ingestions in 2021 versus 0.6% in 2012; five children required mechanical ventilation and two died. It is a hormone, so long-term effects on puberty and reproductive hormones in children are genuinely unstudied, and case reports raise concerns in people with epilepsy and those taking warfarin. Its accepted place is in circadian problems — jet lag and delayed sleep phase — not in chronic insomnia, where the American Academy of Sleep Medicine recommends against it.
What Is Not Known
The boundaries of the section above, in the harvest’s own words. What it excluded, why, and where it looked and found nothing. An absence of evidence is not evidence of absence, and it is not evidence of benefit either.
What Was Left Out, and Why
Quoted from the harvest, where these notes sat above the study list rather than after it. Where a note says “below” it means the studies in the section above.
- Herxheimer & Petrie 2002 Cochrane review of melatonin for jet lag (PMID 12076414, doi 10.1002/14651858.CD001520) was verified end-to-end but omitted: jet lag is not a mental-health outcome, and the delayed sleep phase meta-analysis below carries the same circadian point with quantified phase shifts. Its conclusion (9 of 10 trials positive, NNT 2) is consistent with it.
- Lelak et al., "Pediatric Melatonin Ingestions - United States, 2012-2021", MMWR Morb Mortal Wkly Rep 2022;71(22):725-729 (PMID 35653284, doi 10.15585/mmwr.mm7122a1) was verified via NCBI efetch 2026-08-18 and is quoted in known_risks below rather than entered as a study record; note that PubMed flags an Erratum (MMWR 2022;71(27):885) for it, not a retraction.
- Salanitro 2022 (Neurosci Biobehav Rev, PMID 35691474) verified but omitted as overlapping the two meta-analyses below; its findings point the same way (benefit in delayed sleep phase disorder and in neurodevelopmental disorders, not in general adult insomnia).
The Retraction Check
PubMed efetch records for all five PMIDs inspected 2026-08-18 for "Retraction in", "Expression of concern", "Erratum in", and "Withdrawn" flags; none present.
Questions for a Prescriber or Pharmacist
This page does not tell anyone to take Melatonin or to avoid it. It is not able to: it does not know what else you take, what you have tried, or what you are treating. These are the questions each study above raises, written to be asked out loud.
- The sleep medicine guideline actually recommends against melatonin for ongoing insomnia — if that's what I have, what would you use instead, and is CBT for insomnia available to me?
- If my problem is that I can't fall asleep until 3am rather than that I can't sleep at all, would timed melatonin actually be the right tool — and what time should I take it?
- The pooled evidence says melatonin gets people to sleep about seven minutes sooner — is that worth taking a hormone nightly, or should we look at what's actually keeping me awake?
- Since supplement melatonin has been measured at anywhere from a fifth to nearly five times the label dose, is there a brand you'd trust, or a tested product I should ask for instead?
- If melatonin gummies routinely contain more than the label says — and some contain CBD — is there a form or brand you would actually recommend for my child, or should we not use it?
And the one to ask at the counter, whatever the answers above turn out to be: given everything I am already taking, what would you want to know about Melatonin before I put it in the same body?
Where This Page Comes From
Transcribed from the study-harvest-2026-08-18 record for melatonin, built into this page by scripts/supplement-ingest.mjs on 2026-09-07. Nothing here is fetched at page load, and nothing here was written by a model without a citation behind it.
| Source file | study-harvest/2026-08-18/melatonin.yaml |
|---|---|
| Source repo | REPTechnologies/avalo-backend |
| SHA-256 | 38e5d9138239925908bdcfa0e2a336c037e49117969334b0546a117873a8716f |
| Also searched as | melatonin, Circadin, Slenyto, N-acetyl-5-methoxytryptamine, melatonin gummies |
The Other Substances
- 5-HTP
- Ashwagandha
- Cannabidiol (CBD)
- Cannabis and THC
- Creatine
- Kratom
- L-Theanine
- Magnesium
- Methylene Blue
- Microdosing
- N-Acetylcysteine (NAC)
- Omega-3
- Phenibut
- SAMe
- St John’s Wort
- Valerian
Do any supplements actually work? asks the question across all of them. The full library has the medication records, the funding investigations, and the glossary.