Melatonin is the body's own signal for darkness, a hormone the brain releases at night to set the timing of sleep. It helps most where the problem is timing: jet lag after crossing five or more time zones, and a body clock stuck late. For ordinary insomnia the benefit is small, a few minutes faster to fall asleep.
A low physiologic dose works as well as the high 5 to 10 mg tablets on the shelf, and it leaves less grogginess the next morning. And what is in the bottle often differs sharply from the label, most of all in the gummies given to children.
Findings & Outcomes
What It Is
Melatonin is a hormone the body makes on its own, released into the blood at night and cleared by morning. As a supplement it adds to that night signal. The tablets sold as extra strength, 5 to 10 mg, hold far more than the body makes across a night, which is part of why a small dose is enough and a large one lingers into the morning.
Melatonin is not sold the same way everywhere. In the United States and Canada it sits on the shelf as a supplement. In the United Kingdom, the European Union, Australia, and Japan it is a prescription medicine, available only through a pharmacy or a doctor.
Anatomy of the Practice
1As evening falls
When light fades, a small gland in the brain releases melatonin into the blood. Levels climb through the evening, peak in the middle of the night, and fall before morning. That nightly rise and fall marks biological night for every organ, which is why melatonin is called a chronobiotic, a substance that moves the body clock.
2When you take a dose
A supplement adds to that signal. Taken in the evening it strengthens that night signal and pulls the clock a little earlier. Taken in the morning it signals darkness at the wrong hour and pushes sleep later. The same dose has opposite effects depending on the hour, so the timing matters more than the number of milligrams.
3Why a larger dose does not help
The receptors saturate at low levels, so a physiologic dose near what the body makes is enough to shift the clock. A larger dose does not move the clock any further. It mainly keeps melatonin elevated into the next day, which is the source of next-morning grogginess.
What It Does
Melatonin's effects sort by one thing: how much the sleep problem is a problem of timing. Where the body clock is set to the wrong hour, the effect is large. Where the clock is fine and sleep will not come for other reasons, it is small.
The strongest use is jet lag, taken close to the destination bedtime after flying east across several time zones. Next is a body clock that runs late, where a small evening dose taken hours before the target bedtime pulls the body's own rhythm about 1.2 hours earlier. Shift work sits below both, on weaker evidence, with about 24 more minutes of daytime sleep. Ordinary insomnia sits at the bottom: a few minutes faster to sleep, and the large government-commissioned review found melatonin does little for most sleep disorders once a delayed clock is set aside.
The dose that works is small.
A physiologic 0.3 to 0.5 mg shifts the clock and improves sleep as much as the 3 to 10 mg tablets, so the hour a dose is taken matters more than its size.
Each finding below is graded at the strength of its own evidence.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Sleep
Falls asleep about 7 minutes faster
People fell asleep about seven minutes faster on melatonin than on a dummy pill. The effect is small.
A 2013 meta-analysis (Ferracioli-Oda) pooled 19 randomized placebo-controlled trials in 1,683 people with primary sleep disorders. Melatonin shortened the time taken to fall asleep by 7.06 minutes (95% CI 4.37 to 9.75), increased total sleep time, and improved self-rated sleep quality. The effects were consistent in direction across trials and modest in size, smaller than those usually reported for prescription sleep medication.
The study · 1
Ferracioli-Oda 2013, PLoS One · PLoS One
Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.
About 8 more minutes of sleep, and better ratings
Melatonin added around eight minutes to the night, and people rated their sleep as somewhat better. Again small, and in the same direction across studies.
In the same 2013 meta-analysis of 19 trials (Ferracioli-Oda, 1,683 people), melatonin increased total sleep time by 8.25 minutes (95% CI 1.74 to 14.75) versus placebo and improved overall sleep quality on the scales used. Unusually for a sleep aid, the sleep-quality benefit did not fade with longer use. The magnitude is modest and most trials were short.
The study · 1
Ferracioli-Oda 2013, PLoS One · PLoS One
Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.
For ordinary insomnia, about 7 minutes faster to sleep
For everyday insomnia melatonin trimmed only about seven minutes off the time to fall asleep. The larger 11.7-minute pooled figure is carried by people with a delayed clock, not by ordinary insomnia.
A 2005 meta-analysis (Buscemi) prepared for the US Agency for Healthcare Research and Quality pooled randomized trials of melatonin in primary sleep disorders. Sleep onset latency decreased by 11.7 minutes overall (95% CI -18.2 to -5.2), but the reduction was much larger in delayed sleep phase syndrome (about 38.8 minutes, n=2) than in insomnia (about 7.2 minutes, 95% CI -12.0 to -2.4, n=12). The authors concluded that with short-term use melatonin is not effective for most primary sleep disorders, while it is effective for delayed sleep phase syndrome, and that short-term use appears safe.
The study · 1
Buscemi 2005, J Gen Intern Med · J Gen Intern Med
A 0.3 mg dose works as well as 3 mg
In older adults with insomnia, a small 0.3 mg dose improved sleep as much as 3 mg. The bigger dose also worked, but it kept melatonin high into the next day, which is where next-morning grogginess comes from.
A 2001 double-blind crossover trial (Zhdanova, JCEM) gave older adults with insomnia 0.1, 0.3 or 3 mg of melatonin. The 0.3 mg physiologic dose restored sleep efficiency to normal levels; 3 mg was also effective but raised plasma melatonin far above the normal night-time range and left it elevated during the day, alongside a fall in body temperature. A larger dose was not more effective, and it is the high dose that carries into the next morning.
The study · 1
Zhdanova 2001, J Clin Endocrinol Metab · J Clin Endocrinol Metab
Eases jet lag across five or more time zones
For jet lag, melatonin taken close to bedtime at your destination helps you feel less wrecked, especially after crossing five or more time zones going east. This is one of its strongest uses.
A 2002 Cochrane review (Herxheimer) of 10 randomized trials found melatonin remarkably effective at preventing or reducing jet lag when taken close to the target bedtime at the destination. Benefit was clearest after crossing five or more time zones and traveling east. Doses between 0.5 and 5 mg were similarly effective, though people fell asleep a little faster on 5 mg; doses above 5 mg were no more effective. Timing mattered more than dose, and melatonin taken at the wrong local time could make jet lag worse.
The study · 1
Herxheimer 2002, Cochrane Database Syst Rev · Cochrane Database Syst Rev
Shifts a delayed body clock about 1.2 hours earlier
For people whose clock runs late, who cannot fall asleep until the early hours, a small evening dose pulled the clock earlier, advancing their natural melatonin rise by over an hour and helping them fall asleep sooner.
A 2010 meta-analysis (van Geijlswijk, Sleep) of randomized trials in delayed sleep phase disorder found melatonin advanced the endogenous dim-light melatonin onset by about 1.18 hours and the clock hour of sleep onset by about 0.67 hours, and reduced sleep onset latency by roughly 23 minutes versus placebo. The effect depends on a low dose taken several hours before the desired bedtime, timed to each person's own clock, not at bedtime itself.
The study · 1
van Geijlswijk 2010, Sleep · Sleep
Recommended for a delayed clock and faster sleep onset in primary insomnia
A 2017 review concluded melatonin helps for a delayed body clock and for shortening how long it takes to fall asleep in primary insomnia, working by shifting the body clock rather than as a general sedative.
A 2017 systematic review (Auld, Sleep Medicine Reviews) of randomized controlled trials concluded that exogenous melatonin reduces sleep onset latency in primary insomnia, is effective in delayed sleep-wake phase disorder, and helps regulate the sleep-wake cycle in people who are blind, while focusing on primary sleep disorders rather than insomnia secondary to another medical or psychiatric condition. It reinforced that melatonin acts as a chronobiotic that shifts the timing of sleep, rather than as a sedative.
The study · 1
Auld 2017, Sleep Med Rev · Sleep Med Rev
Evening doses shift the clock earlier, morning doses later; 0.5 mg does it as much as 3 mg
Melatonin is a timing signal, not a sedative. Taken in the afternoon or evening it moves your clock earlier; taken in the morning it moves it later. A tiny 0.5 mg dose shifted the clock as much as a 3 mg dose.
A 2010 laboratory study (Burgess, JCEM) mapped the human phase-response curve to three days of daily melatonin at 0.5 mg versus 3.0 mg. Both doses produced phase advances of similar size, largest when melatonin was taken in the afternoon and early evening, and phase delays when taken in the morning. The 0.5 mg dose shifted the clock as much as 3.0 mg, evidence that melatonin's circadian action does not need a large dose.
Who this may not transfer to:Measured in a small group of healthy adults under controlled light; the exact clock time that shifts one person's rhythm varies between people.
The study · 1
Burgess 2010, J Clin Endocrinol Metab · J Clin Endocrinol Metab
About 24 more minutes of daytime sleep after night shifts
For night-shift workers sleeping in the day, melatonin lengthened daytime sleep by around 24 minutes, and night-time sleep by about 17 minutes. It did not help them fall asleep faster, and the evidence is not strong.
A 2014 Cochrane review (Liira) pooling randomized trials in shift workers found melatonin increased daytime sleep by about 24 minutes (7 trials) and night-time sleep by about 17 minutes versus placebo, but did not shorten sleep onset latency or improve other sleep-quality measures. The reviewers rated the evidence low quality. In shift work, melatonin acts as a timing aid alongside deliberate light exposure, rather than as a reliable sleep extender.
The study · 1
Liira 2014, Cochrane Database Syst Rev · Cochrane Database Syst Rev
How It Works
Melatonin is the body clock's output signal, released to mark biological night. The master clock in the brain receives light through the eyes, and in darkness it prompts the pineal gland to release melatonin, which then feeds back to the clock and to the rest of the body. Because melatonin is a timing signal, its effect depends on when it reaches the clock. A dose in the afternoon or early evening moves the clock earlier and brings sleep forward. A dose in the morning moves it later. This is the human phase-response curve, and it explains why melatonin taken casually at bedtime can shift a clock the wrong way when the timing is off.
A sleeping pill works by a different route. A sedative dampens the nervous system, so sleep comes wherever the clock happens to sit. Melatonin moves the clock, so sleep arrives once the clock is reset. That is why melatonin does so little for ordinary insomnia, where the clock is already on time, and so much more for a clock set to the wrong hour. For the light half of the same system, see evening light and screens and morning light.
What Changed
Most people meet melatonin as a natural sleeping pill: take 5 or 10 milligrams to fall asleep, and if it does not work, take more. That mental model is what leads to the wrong dose at the wrong hour.
The evidence points the other way on both counts. A physiologic dose in the range of half a milligram to one milligram shifts the clock and improves sleep as well as the high doses do. The larger tablets mostly leave melatonin circulating into the daytime and cause the morning grogginess, and they do not move the clock any further. The shelves are stacked with 5 and 10 mg products out of commercial habit, not because more milligrams work better.
Getting It Right
Ways to Do It
Melatonin works for problems of timing, at a small dose and the right hour. The steps below start with the behavioral basics that outdo it for ordinary sleeplessness, then cover the situations where it earns a place and how to use it. This section is educational; where melatonin is a prescription medicine, as in the UK, EU, Australia, and Japan, work these through with a pharmacist or doctor. Start at the top and read the rungs that fit your situation.
For most trouble sleeping, the changes with the strongest evidence are behavioral. A consistent wake time, a dim evening, and for long-term insomnia the structured program called CBT-I all outdo melatonin for ordinary sleeplessness. Work through the sleep environment and evening light first. Melatonin works best added on top of those, once they are in place.
Melatonin does the most for jet lag, a body clock that runs late (delayed sleep phase), and shift work, where the clock is set to the wrong time. If you lie awake at a normal bedtime for other reasons, it is likely to do little, and the fix is more often behavioral or medical.
A physiologic dose near what the body makes, roughly 0.5 to 1 mg, worked as well in the trials as the 5 to 10 mg tablets and is less likely to leave grogginess the next morning. A larger tablet can often be split. More is not stronger here.
The hour you take melatonin sets what it does. For jet lag, the trials used a dose close to the destination bedtime on arrival, especially after flying east across five or more time zones. For a delayed clock, a small dose several hours before the target bedtime, in the early evening, pulls sleep earlier; a morning dose shifts the clock the other way.
Because content varies widely from the label, a product carrying an independent testing mark such as USP Verified or NSF comes closest to the dose on the box. A plain low-dose tablet is more consistent than a gummy. Store any melatonin out of a child's reach; the flavored versions are easy for a child to overeat.
Go Deeper
- CBT-I: the structured behavioral program every guideline names first for long-term insomnia, ahead of any supplement.
- Evening light and screens: the light half of the same clock, and the free changes that let your own melatonin rise on time.
- The sleep environment: the room changes that help sleep hold together, none of which cost anything.
- Insomnia: the whole picture, the Chinese medicine patterns, and where melatonin fits among the things that help.
The Chinese Medicine View
Melatonin is a hormone identified in the twentieth century, so it has no entry in the classical Chinese pharmacopoeia: no channel it enters, no temperature or flavor, no historical text that names it. What follows places it inside the framework as a lens, not as evidence, and it invents no traditional quotation, because none exists.
The tradition reads the day as a movement between Yin and Yang. Yang is active, outward and bright and governs the daytime; Yin is quiet, inward and dark and governs the night. Sleep is what happens when Yang withdraws and the Shen, the spirit that lives in the Heart, settles inward and rests. Melatonin is the body's chemical signal of darkness, the marker that biological night has come, so as a modern description it sits close to the moment the tradition calls Yang folding into Yin at nightfall. That is a fair place to set it, and no more than that. Melatonin is a hormone measured in the blood; Yin and Shen are categories in a different language laid over the same nights. Neither one validates the other.
Read this way, the tradition would also be wary of the sleeping-pill habit. It does not treat every sleepless night as one problem with one fix. Waking around three in the morning with a dry mouth and a red tongue is read as empty heat from Yin deficiency; lying awake with a churning, agitated mind is read differently again, and each has its own pattern and treatment. A person for whom the clock itself is misaligned, the traveler or the night worker, is close to what melatonin actually corrects; a person whose Shen will not settle for other reasons is not, and reaching for a higher dose would be the wrong move in either language. The full differentiation lives in the insomnia guide.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Actual dose ran from 83% below to 478% above the label
A 2017 analysis (Erland, J Clin Sleep Med) measured melatonin in 31 commercial supplements. Actual content ranged from 83 percent below to 478 percent above the labeled amount, more than 71 percent of products fell outside 10 percent of their own label, and lot-to-lot variability within a single product reached 465 percent. Eight of the 31 products, about 26 percent, also contained serotonin. Because supplements are not held to the content-accuracy standards of medicines, the dose a person actually takes can differ greatly from the number on the box.Erland 2017, J Clin Sleep Med
Gummies ran from 74% to 347% of the labeled dose, and one had none
A 2023 analysis (Cohen, JAMA) tested 25 melatonin gummy products sold in the United States. 22 of the 25 (88 percent) were inaccurately labeled. Among the 24 products that contained detectable melatonin, actual content ranged from 74 to 347 percent of the labeled amount; one product contained no detectable melatonin, and some also contained cannabidiol at variable amounts. Gummies are the form most often given to children, which makes the inconsistency and the chance of an unintended large dose more consequential.Cohen 2023, JAMA
Accidental child ingestions rose 530% from 2012 to 2021
A 2022 report (Lelak, MMWR) analyzed US poison-control data and found pediatric melatonin ingestions rose 530 percent between 2012 and 2021, with more than 260,000 ingestions reported over the decade and melatonin becoming the most frequently ingested substance among young children by 2020. The large majority of children were asymptomatic; roughly 4,000 required hospitalization, a smaller number needed intensive care, and two deaths were reported. The rise tracks the spread of flavored, palatable products left within a child's reach.Lelak 2022, MMWR Morb Mortal Wkly Rep
Short-term side effects are usually mild
A 2019 systematic review (Besag, CNS Drugs) of adverse events in randomized trials of melatonin for sleep disorders found the most frequently reported effects were daytime sleepiness, headache, other sleep-related events, dizziness and hypothermia. These were generally mild and transient, with no consistent serious adverse events in short-term use. Next-day grogginess is more likely with larger doses and with doses taken too late, which keep melatonin elevated into the morning.Besag 2019, CNS Drugs
Few problems over months to a few years; the long term is untested
A 2022 systematic review (Besag, Expert Opinion on Drug Safety) of long-term melatonin studies found that adverse events reported over months to a few years were few and generally mild. Long-duration human data, particularly in children, remain limited. The reassurance covers the medium term; the very long term and childhood development are still open questions.Besag 2022, Expert Opin Drug Saf
Children: a decision to make with a clinician
Melatonin is widely given to children, but the dose in a product is unreliable, the flavored gummies are easy for a child to overeat, and the long-term effect on a developing child, including the timing of puberty, is not well studied. Behavioral approaches come first for children's sleep. If melatonin is being considered, particularly for a child with autism or ADHD where the evidence is stronger, make the decision with the child's clinician, and store it out of reach.
Pregnancy and breastfeeding
There is little safety data on supplemental melatonin during pregnancy or breastfeeding, and doses far above the body's own output have not been well studied here. Talk it through with your obstetrician or midwife before starting.
Medication interactions to check
Melatonin can add to the effect of blood-thinning medicines such as warfarin and antiplatelet drugs, and it is biologically active in the immune system, so it warrants caution with immunosuppressant medication. It may also interact with sedatives, blood-pressure and diabetes medicines, and drugs that affect the liver enzyme that clears it. If you take regular medication, check with a pharmacist or clinician before adding it.
Next-day grogginess and driving
A dose that is too large or taken too late keeps melatonin circulating into the morning, which can leave you groggy and slow. A smaller, earlier dose reduces this. Until you know how it affects you, be cautious about driving or operating machinery the next morning.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does melatonin actually help you sleep?
For ordinary insomnia, a little. Pooled trials show people fall asleep about seven minutes faster and gain a few minutes of sleep, a small effect. Where melatonin clearly helps is timing problems: jet lag, a body clock set too late, and to a lesser degree shift work. If you lie awake at a normal bedtime for reasons unrelated to your clock, behavioral approaches, and for long-term insomnia CBT-I, have stronger evidence than melatonin.
How much should I take, and when?
Less than most bottles suggest. A physiologic dose of about 0.5 to 1 mg works as well as the common 5 to 10 mg tablets and is less likely to leave you groggy. Timing matters more than the amount. For jet lag, the trials used a dose near the destination bedtime. For a clock that runs late, a small dose a few hours before the target bedtime, in the early evening, shifts sleep earlier, while a morning dose shifts the clock the wrong way. In the UK, EU, Australia, and Japan melatonin is a prescription medicine, so the amount and form come through a pharmacist or doctor.
Is melatonin safe for children?
It is widely used in children, but a few things call for care. The dose in a product often differs from the label, gummies are easy for a child to take too many of, and accidental ingestions have risen sharply as those products spread. The long-term effect on a developing child is not well studied. Behavioral sleep steps come first, and if melatonin is being considered, especially for a child with autism or ADHD, it is a decision to make with the child's clinician, with the supplement stored out of reach.
Will I feel groggy the next day, and is it habit-forming?
Grogginess is the most common complaint. It comes from a dose that is too large or taken too late, which leaves melatonin circulating in the morning. A smaller, earlier dose usually fixes it. Melatonin is not thought to be physically addictive the way sedatives can be, though some people find the nightly routine hard to give up. Other reported effects, headache, dizziness, and vivid dreams, are usually mild.
The products vary so much, so which should I buy?
Because supplements are not held to the content-accuracy rules that govern medicines, independent testing has found the actual amount ranging from well below to several times above the label, with serotonin present in some products. Choose a plain low-dose tablet carrying an independent testing mark such as USP Verified or NSF, kept at the lowest effective dose. Gummies are the least consistent form. What matters is a reliable dose, so pick the product most likely to contain what its label says.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 14 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 8, 2026.
Evidence strength
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