Melatonin is usually the first thing people try, and the one they end up least sure about. It needs no prescription in the US, and it has a reputation somewhere between a vitamin and a sleeping pill. That last part is where most of the confusion starts, because it is neither.
The short answer is that melatonin works well for specific things related to sleep, but not as a general solution for insomnia. It's a timing signal rather than a sedative: for a body clock that has landed in the wrong time zone it is genuinely effective, and for months of broken nights the people who write the treatment guidelines advise against it.
There's also a complication sitting underneath the whole question. Most people arguing about whether melatonin worked for them don't know how much they took. Two separate research teams have taken these products into a lab and measured what was actually inside, and the amount on the label and the amount in the pill are frequently different, occasionally by a wide margin. The dose, the one variable everybody assumes they control, is shakier than it looks.
Does Melatonin Work for Sleep, or Just for Jet Lag?
Melatonin is a hormone the brain already makes. The pineal gland releases it once darkness falls, levels peak in the middle of the night, and its job is to tell the rest of the body what time it is [1]. That is a different job from knocking you out, which is why it behaves so unlike a sleeping pill.
Where the problem genuinely is timing, it performs. Jet lag is a clock that landed in the wrong time zone, and the Cochrane review of trials in air travelers is unusually enthusiastic, calling melatonin "remarkably effective" at preventing or reducing jet lag for adults crossing five or more time zones [2].
It isn't inert the rest of the time either. Pooling 26 randomized trials, researchers found melatonin does shorten how long people take to fall asleep and does add a little total sleep, with results that depend heavily on timing [3]. Modest is the honest word, and modest is not what sleep medicine reaches for with chronic insomnia: the American Academy of Sleep Medicine's guideline on sleep drugs suggests clinicians not use melatonin, for either falling asleep or staying asleep [4]. Europe's medicines regulator was similarly restrained about its own approved version, concluding the drug "has only been shown to have a small effect in a relatively small number of patients" while judging the benefits still worth it [1].
Timing is also what sets the ceiling. Researchers mapped this by giving people melatonin at different points in the day and measuring which way their body clock moved: taken in the afternoon or early evening it pulls the clock earlier, taken in the morning it pushes the clock later, and across the first half of the night, when almost everyone actually takes it, there is a dead zone where it barely moves the clock at all [5]. That matters most once melatonin has become a 2am decision, because a pill taken after a middle-of-the-night waking lands either where it does nothing to your timing or where it pushes it later, which is the opposite of what the person reaching for it wants.
What's Actually Inside a Melatonin Gummy?
The first study is the one people have usually half-heard about. In 2017, Lauren Erland and Praveen Saxena bought 31 melatonin supplements from grocery stores and pharmacies in Guelph, Ontario, ran them through liquid chromatography, and published the results in the Journal of Clinical Sleep Medicine. The actual melatonin content ranged from 83% below the label to 478% above it. More than 71% of the products missed their own label claim by more than 10%. Two lots of the same product could differ by as much as 465%, so a brand that worked one month was not necessarily the same product the next [6].
The second study, in 2023, went after gummies specifically. Pieter Cohen's team bought 25 products and found 22 of them inaccurately labeled, with actual melatonin running from 74% to 347% of what the package claimed. One contained no detectable melatonin at all, only 31.3 mg of cannabidiol (CBD). Measured across the set, servings held anywhere from 1.3 mg to 13.1 mg, a tenfold spread between products a shopper would treat as interchangeable [7].
The reason a product can miss its own label by that much isn't a scandal so much as a category. In both countries melatonin is sold as a supplement rather than as a medicine, and in the US that means the FDA does not approve it for safety or effectiveness, or clear its labeling, before it reaches the shelf [8]. Nobody checked the number on the box on its way to you.
The products that do get checked are largely the ones that volunteer. ConsumerLab, a private testing company that sells both subscriptions to its results and a certification seal to manufacturers, reported that every melatonin supplement in its 2024 round matched its label within a reasonable margin, but it chooses which products to test, two of the twenty reached it through that opt-in certification program, and it noted the result was better than what researchers find when they sample the market blind [9]. Which is the distinction worth keeping: the brands confident enough to be tested came out fine, and the shelf as a whole still hasn't been.
How freely it's sold depends entirely on where you live, which is worth knowing if you have ever gone looking for melatonin abroad and couldn't find it. In the UK, for example, it is prescription-only [10].
Which is the part no label can help with: what dose is right for you. If you take melatonin most nights, or take anything else alongside it, ask a pharmacist or your doctor, because they can see your full medication list, and that is what actually decides whether melatonin is a good idea for you and in what amount.
There's also a lever the label never touches. Whatever you take lands on top of the melatonin your own body is already producing, or failing to produce, and that part depends on how you spend the hours before bed.
Your Evenings Are Suppressing Your Own Melatonin
This is the more interesting lever, because ordinary evenings work against the melatonin people already produce.
Researchers at Brigham and Women's Hospital compared 116 healthy adults living under normal room light against people kept in dim light for the eight hours before bed. Room light, under 200 lux, delayed the onset of melatonin in 99% of them and cut roughly 90 minutes off the window in which their bodies made it. Light during the usual hours of sleep suppressed it by more than half in 85% of trials [11]. Note the comparison there: not a phone, a room with the lights on.
Screens add to it. In a later study from the same lab, adults reading on a light-emitting e-reader before bed took longer to fall asleep, produced less melatonin, shifted their body clock later, and woke less alert than when they read a printed book [12].
Which points at a short list of habits, all free. Bring the lights down for the two to three hours before bed, and count the overhead ones, not just the phone. Get outside in the morning, since daylight is the signal that anchors the whole cycle. Keep your wake time steady, including on weekends, because the rhythm you are trying to strengthen runs on regularity more than on any single evening.
Why Melatonin Is Not A Solution for Insomnia
Even a perfectly accurate label wouldn't matter if your sleep problems have been going on for months. That kind of insomnia isn't caused by a melatonin shortage, which is why the AASM's guidance on melatonin and insomnia points clinicians away from it [4]. What keeps it going is what builds up around the bad nights: the clock math at 3am, the earlier bedtimes to catch up, the bed turning into a cue for effort instead of sleep [13].
That pattern answers to something else. Cognitive Behavioral Therapy for Insomnia (CBT-I) is what sleep medicine puts first for chronic insomnia [14], and its most counterintuitive component is the one nobody volunteers for: less time in bed, not more, so sleep consolidates. That's how sleep restriction therapy works, and years of bad nights don't disqualify you, because you can still rebuild your sleep.
Rest is a program built on the behavioral principles of CBT-I, plus circadian biology and neuroscience, together with world-class sleep experts from institutions like UCSF and Stanford. It coaches those changes in short daily conversations, by text or by voice, and adjusts as the nights change.
The Questions People Keep Asking
Does melatonin work for insomnia? For insomnia that has lasted months, the American Academy of Sleep Medicine's guideline on sleep medications suggests clinicians not use melatonin, for either falling asleep or staying asleep [4]. Pooled trials do show a modest effect on how fast people fall asleep [3].
Does melatonin help with jet lag? Yes, and this is its strongest use. A Cochrane review of trials in air travelers described melatonin as remarkably effective at preventing or reducing jet lag for adults crossing five or more time zones [2], because jet lag is a clock alignment problem and melatonin is a clock signal.
Why did melatonin stop working for me? Two ordinary explanations come before tolerance. The amount you are actually getting can vary between bottles of the same product [6] [7], and melatonin was never aimed at the pattern that keeps chronic insomnia going, so any early benefit was likely to be small and easy to lose.
What's Next
Melatonin has real uses, but it is not a permanent solution. It's a timing signal, sold — in the US at least — in amounts nobody verified on the way to the shelf. If what you have is a clock in the wrong place, a week of jet lag or a schedule that shifted, that may be all you need. If what you have is months of broken nights, the milligrams were never the variable.
If your nights come apart in the middle, or you lie there doing arithmetic about how much sleep is left, that part is behavior and conditioning, and it shifts with practice and feedback.
That is the part Rest works on. It's a program built on the behavioral principles of CBT-I, delivered as a short conversation each morning, by text or by voice, that reads how you actually slept and sets up the day around it. Start with Rest »
Disclaimer. This article is published for general information only. It is not medical advice or a diagnosis, and nothing here is a recommendation to take, avoid, or change any supplement or medication. Rest is not a substitute for professional medical care. Do not start, stop, or adjust a treatment, including a prescribed sleep medication, without talking to your clinician.
Citations
European Medicines Agency. Circadin (melatonin) — European public assessment report, EMEA/H/C/000695. https://www.ema.europa.eu/en/medicines/human/EPAR/circadin (accessed August 2026) — Melatonin described as a hormone produced by the pineal gland, with blood levels rising after the onset of darkness and peaking in the middle of the night; 2 mg prolonged-release tablet, prescription only, authorized 29 June 2007 for short-term treatment of primary insomnia in patients aged 55 or over; across three trials in 681 patients, 32% on Circadin reported significant improvement after three weeks versus 19% on placebo; the CHMP concluded the medicine "has only been shown to have a small effect in a relatively small number of patients" while judging benefits greater than risks; uncommon side effects (1–10 per 1,000) include insomnia, irritability, nervousness, restlessness, abnormal dreams, anxiety, migraine, lethargy, dizziness and somnolence.
Herxheimer, A., & Petrie, K. J. (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, (2), CD001520. https://doi.org/10.1002/14651858.CD001520 — "Melatonin is remarkably effective in preventing or reducing jet-lag"; recommended for adult travelers crossing five or more time zones. A circadian-timing use, not a sedative one.
Cruz-Sanabria, F., Bruno, S., Crippa, A., Frumento, P., Scarselli, M., Skene, D. J., & Faraguna, U. (2024). Optimizing the time and dose of melatonin as a sleep-promoting drug: A systematic review of randomized controlled trials and dose-response meta-analysis. Journal of Pineal Research, 76(5), e12985. https://doi.org/10.1111/jpi.12985 — 26 randomized controlled trials, 1,689 observations, in patients with insomnia and healthy volunteers; melatonin gradually reduced sleep onset latency and increased total sleep time, with efficacy dependent on timing relative to bedtime.
Sateia, M. J., Buysse, D. J., Krystal, A. D., Neubauer, D. N., & Heald, J. L. (2017). Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults: An American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine, 13(2), 307–349. https://doi.org/10.5664/jcsm.6470 — "We suggest that clinicians not use melatonin as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults" (WEAK recommendation).
Burgess, H. J., Revell, V. L., & Eastman, C. I. (2008). A three pulse phase response curve to three milligrams of melatonin in humans. The Journal of Physiology, 586(2), 639–647. https://doi.org/10.1113/jphysiol.2007.143180 — 27 healthy subjects; phase-advance portion of the curve peaks about 5 hours before dim-light melatonin onset, in the afternoon; the phase-delay portion peaks about 11 hours after dim-light melatonin onset, shortly after usual morning waking; a dead zone of minimal phase shifts occurs around the first half of habitual sleep; maximum fitted shifts 1.8 hours advance and 1.3 hours delay. The authors note that using melatonin as a sleep aid at night has minimal phase-shifting effect.
Erland, L. A. E., & Saxena, P. K. (2017). Melatonin natural health products and supplements: Presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine, 13(2), 275–281. https://doi.org/10.5664/jcsm.6462 — 31 commercial supplements analyzed by ultraperformance liquid chromatography; melatonin content ranged from −83% to +478% of the labeled content; lot-to-lot variability within a single product up to 465%; more than 71% failed to meet label claim within a 10% margin; serotonin identified in eight supplements (26%) at 1 to 75 μg.
Cohen, P. A., Avula, B., Wang, Y. H., Katragunta, K., & Khan, I. (2023). Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA, 329(16), 1401–1402. https://doi.org/10.1001/jama.2023.2296 — 25 gummy products analyzed; 22 (88%) inaccurately labeled and only 3 within ±10% of the declared quantity; actual melatonin 74% to 347% of label, 1.3 mg to 13.1 mg per serving; one product contained no detectable melatonin but 31.3 mg of CBD; serotonin was not detected in any product.
U.S. Food and Drug Administration. FDA 101: Dietary Supplements. https://www.fda.gov/consumers/consumer-updates/fda-101-dietary-supplements (accessed August 2026) — "The FDA does NOT have the authority to approve dietary supplements for safety and effectiveness, or to approve their labeling, before the supplements are sold to the public."
ConsumerLab. Melatonin Supplements Review & Top Picks (products tested 2024; page latest update 8 June 2026). https://www.consumerlab.com/reviews/melatonin-supplements/melatonin/ (accessed August 2026) — Independent HPLC testing commissioned by ConsumerLab, with product identities withheld from the laboratories; the review's public summary states that all melatonin supplements tested "contain their listed amounts of melatonin within a reasonable margin," and that this "is better than other researchers have found when sampling the market." Sample composition from the accompanying release, ConsumerLab Tests Identify Best Melatonin Supplements (1 February 2024), https://www.consumerlab.com/news/best-melatonin-supplements-2024/02-01-2024/: 20 products, of which 18 were selected by ConsumerLab and 2 were approved through its voluntary Quality Certification Program, which manufacturers opt into; melatonin per suggested serving ranged from 0.3 mg to 11.4 mg. Not peer-reviewed. ConsumerLab sells subscriptions to the full results and sells certification to manufacturers, and the per-product table is members-only, so individual figures could not be verified against a primary record.
UK Department of Health and Social Care, written answer to Parliamentary Question UIN 4948, answered 8 June 2026. https://www.theyworkforyou.com/wrans/?id=2026-05-29.4948.h (accessed August 2026) — "In the UK, melatonin is regulated as a prescription only medicine," classified by the Medicines and Healthcare products Regulatory Agency (MHRA) under the Human Medicines Regulations 2012; the answer notes that other countries, for example the United States, may allow melatonin to be sold over the counter or as a supplement. Pharmacokinetics and UK prescription classification of the licensed product from Circadin 2 mg Prolonged-release Tablets, Summary of Product Characteristics (Flynn Pharma, PLGB 52348/0002), https://www.medicines.org.uk/emc/product/2809/smpc (accessed August 2026): listed as a prescription only medicine, terminal half-life 3.5–4 hours, elimination by renal excretion of metabolites (89% as sulphated and glucuronide conjugates of 6-hydroxymelatonin, 2% as unchanged melatonin).
Gooley, J. J., Chamberlain, K., Smith, K. A., Khalsa, S. B. S., Rajaratnam, S. M. W., Van Reen, E., Zeitzer, J. M., Czeisler, C. A., & Lockley, S. W. (2011). Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. The Journal of Clinical Endocrinology & Metabolism, 96(3), E463–E472. https://doi.org/10.1210/jc.2010-2098 — 116 healthy volunteers aged 18–30; room light (<200 lux) versus dim light (<3 lux) in the eight hours before bedtime; room light produced a later melatonin onset in 99.0% of individuals and shortened melatonin duration by about 90 minutes; light during the usual hours of sleep suppressed melatonin by more than 50% in 85% of trials.
Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232–1237. https://doi.org/10.1073/pnas.1418490112 — Reading on a light-emitting device before bed, compared with a printed book, lengthened time to fall asleep, reduced evening sleepiness and melatonin secretion, delayed circadian timing, and reduced next-morning alertness.
Perlis, M. L., Smith, M. T., Benson-Jungquist, C., & Posner, D. A. (2005). Cognitive Behavioral Treatment of Insomnia: A Session-by-Session Guide. New York: Springer. https://doi.org/10.1007/0-387-29180-6 — Conditioned arousal and stimulus control: the bed and bedroom become cues for wakefulness and effort rather than for sleep.
Edinger, J. D., Arnedt, J. T., Bertisch, S. M., et al. (2021). Behavioral and psychological treatments for chronic insomnia disorder in adults: An American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine, 17(2), 255–262. https://doi.org/10.5664/jcsm.8986 — CBT-I as first-line treatment for chronic insomnia in adults, with sleep restriction (reducing time in bed) among the recommended components.