The best-supported melatonin dosage is a small one: about 0.5 to 3 mg, taken 2 to 3 hours before bed. Pooled results from 26 trials show sleep improving up to about 4 mg, then levelling off, so 5 and 10 mg tablets add nothing (Meta-analysis). When you take it matters just as much. The best gap was about 3 hours before the target bedtime, not 30 minutes.
What Melatonin Actually Does
Melatonin is a hormone your brain makes when it gets dark. It tells your body clock that night has started, and that is the whole message. Sleeping pills work by sedating you. Melatonin only passes on the time.
So the effect is small, which is part of why people keep raising the dose. Across 19 trials in 1,683 adults and children, melatonin cut about 7 minutes off the time it took to fall asleep. It added about 8 minutes of sleep (Meta-analysis). The researchers called that modest, and smaller than what prescription sleeping pills give.
People with diagnosed insomnia get similar numbers. A 2023 review pooled 22 trials of melatonin and a related sleep drug, covering 4,875 people. Among the 925 who took melatonin, the slow-release form may shave about 5 to 6 minutes off the wait (Meta-analysis).
Five minutes is less than the bottle seems to promise. So people buy a bigger one: 3 mg, then 5, then 10. That gets two things wrong at once, how much you take and when you take it.
The Dose Where Benefit Stops
In 2024 a team pooled 26 trials published between 1987 and 2020 (Meta-analysis). Each trial decided by coin flip who got melatonin and who got a dummy pill. Together they held 1,689 measurements.
The team then plotted benefit against dose, which most reviews never do. Sleep came faster and lasted longer as the dose went up. At about 4 mg the line went flat.
That result cuts both ways. The authors were not arguing for tiny doses, and they suggested clinics move up from the common 2 mg to 4 mg (Meta-analysis). What it rules out is the drugstore shelf. At 5, 10 or 20 mg you are past the point where extra milligrams help.
An older trial shows what those extra milligrams do instead. Thirty adults over 50 took a dummy pill, then 0.1, 0.3 and 3 mg on separate weeks, in an order set by chance (Trial). Among the 15 poor sleepers, 0.3 mg worked best. They slept through 88% of their time in bed on that dose, against 78% on the dummy pill and 84% on 3 mg. Each dose was only compared with the dummy pill, so treat this as a hint rather than a verdict.
The 3 mg dose left a trace. Melatonin from it was still in the blood well into the next day (Trial). Doses of 0.1 to 0.3 mg land near the amount your body makes on its own. Standard 1 to 5 mg pills push blood levels 10 to 100 times past that natural night-time peak (Review). A 2014 review of 16 studies in older adults put it simply: use the lowest dose of a plain, fast-release tablet that works (Systematic review).
Big doses are wasteful, but the evidence does not say they are dangerous. One review searched 79 trials of melatonin at 10 mg or more, covering 3,861 adults (Meta-analysis). Only 4 of those trials were solid enough to pool together. In those 4, minor complaints came up more often than on the dummy pill: drowsiness, headache and dizziness. Serious problems were no more common, and no more people dropped out.
That evidence is thinner than it sounds. Nearly 3 in every 10 of the 79 trials never mentioned side effects at all (Meta-analysis). The authors asked for better long-term trials before anyone calls the question settled.
So the case against a 10 mg tablet is simple. It buys you nothing over a 1 mg tablet, and it leaves melatonin in your blood at breakfast.
Timing Is the Other Lever
The 2024 analysis also asked what predicted how fast people fell asleep. Two things did. The bigger one was whether a person had insomnia to begin with. The other was the gap between swallowing the dose and going to sleep (Meta-analysis).
The size of the dose was not on that list, since it was handled separately. So the hour you take it is not a footnote to the milligrams. It is the part most people never adjust.
The same group repeated the work in children with a neurological or mental health condition, pooling 21 studies (Meta-analysis). Again, the earlier the dose came before bedtime, the faster the children fell asleep. The authors suggest 2 to 4 mg about 3 hours before bed, if bigger trials back that up.
The reason is simple. You are trying to move a clock forward. Your own melatonin starts rising a couple of hours before you feel sleepy. A tablet swallowed at lights-out arrives after that signal has gone out, so it adds little.
Researchers have mapped this with phase-response curves. These chart how far a dose moves the clock, depending on the hour you take it. In 34 healthy adults, 0.5 mg moved the clock up to about 1.5 hours earlier (Trial). The same lab’s earlier 3 mg curve managed about 1.8 hours (Trial). That is six times the dose for almost no extra shift. An editorial in the same journal said the two doses cause much the same shift (Editorial).
The hour did matter. The biggest forward shifts came when 0.5 mg was taken in the afternoon, roughly 9 to 11 hours before the middle of the night’s sleep (Trial). If you sleep from midnight to 8am, that window falls in late afternoon or early evening. Melatonin taken at bedtime barely moved the clock at all (Trial).
Two cautions here. People vary a lot, and some in that trial shifted by nearly 3 hours. The small dose also gave a messier picture than the large one (Trial). Light pushes the clock the other way, which is why morning light is the other half of the job. A bright screen after your dose can cancel the message you just sent.
Where Melatonin Genuinely Works
Jet lag is melatonin’s best case, because jet lag is a clock problem. A Cochrane review from 2002 found 10 trials (Systematic review). Eight of them showed less jet lag after flights crossing five or more time zones. People took the melatonin close to bedtime at the destination, between 10pm and midnight.
The size of that benefit is unusual for a supplement. Only two trials reported enough detail to count it. In those two, about one traveller in every two was helped (Systematic review).
The dose again made little difference. Anything from 0.5 to 5 mg worked about as well, though people did fall asleep faster on 5 mg than on 0.5 mg. Above 5 mg nothing improved (Systematic review).
The form of the tablet mattered more than the milligrams. A 2 mg slow-release version did little, which hints that a short sharp peak beats a slow trickle (Systematic review). Those trials point to a plain, fast-dissolving tablet.
The benefit is likely to grow with the number of time zones you cross, and it is smaller flying west than east. Take it at the wrong hour, early in the destination day, and it can leave you sleepy and slow to adjust (Systematic review).
There is one caveat. A follow-up search in 2008 found no new trials to add, and nobody has revisited the review since (Systematic review). The evidence is real, but it is old.
The same reasoning covers night shifts and a body clock that simply runs late. In both cases the clock sits in the wrong place, and the phase-response work says melatonin can move it (Trial).
So for an eastward flight over five or more zones, take a plain 0.5 to 5 mg tablet at bedtime on arrival, for the first few nights. That is later than the sleep trials favour, but the jet lag trials dosed at bedtime.
Insomnia Is a Different Problem
Long-running insomnia is another matter. The American Academy of Sleep Medicine reviewed the evidence and suggested that clinicians not use melatonin for trouble falling or staying asleep (Guideline).
The guideline calls that a weak recommendation, and it explains the word. Weak means the evidence is uncertain, not that the drug has been proved useless (Guideline). No drug in the whole guideline earned a strong recommendation either way.
The same guideline is much firmer about the alternative. It says everyone with chronic insomnia should get cognitive behavioural therapy for insomnia as a first treatment (Guideline). The numbers explain why. One analysis pooled 13 trials in 823 adults to compare the two starting points. Months later, about 41 in every 100 who began with CBT-I no longer counted as having insomnia, against 28 in every 100 who began on sleeping pills (Meta-analysis). Fewer people quit the therapy than quit the drugs.
It may hold up in harder cases too. One review gathered 37 trials where insomnia sat on top of another medical or mental health problem. In the 22 trials that measured it, 36 in every 100 were free of insomnia right after the therapy, against 17 in every 100 in the comparison groups (Meta-analysis). Those counts came from sleep questionnaires, not a fresh diagnosis.
Melatonin is not the only thing people reach for here. Two other common answers are magnesium and a more regular sleep schedule, each covered in its own piece. Neither one replaces the therapy.
What the Label Does Not Say
Taking less is harder than it sounds, because the number on the bottle is often wrong.
Researchers bought 31 melatonin products from 16 brands in Canadian shops and measured them (Study). Content ran from 83% below the label to 478% above it. More than 7 in every 10 missed their own label by more than a tenth. One chewable tablet varied more than fourfold between its own batches. Serotonin, which does not belong in the bottle, turned up in 8 of the 31.
That testing was done in 2017, and later work found the same thing. A lab bought 25 melatonin gummies in the US and found 22 of them mislabelled (Study). Measured content ran from 74% to 347% of what the package claimed. One product sold as melatonin with CBD held no melatonin at all, just 31 mg of CBD.
An FDA laboratory then tested 110 children’s melatonin products sold in the US (Study). Content ran from none at all to nearly seven times the label. A 2025 European analysis of 50 products found a similar spread, from 71% to 182% of the stated amount (Study).
The rules differ by country. In much of Europe, the UK and Australia, melatonin is a prescription medicine. In the US it is sold as a supplement, under lighter rules. Neither system is a guarantee. In that European testing, 3 of the 25 products from legal sellers broke the rules (Study). They either made claims they were not allowed to make, or packed more than triple the daily dose Belgium allows.
Independent testing is rare. In its 2022 advisory, the American Academy of Sleep Medicine noted that only four melatonin products had earned the USP Verified Mark. All four were 3 mg or 5 mg (Advisory).
One more issue involves children. US poison centres logged 260,435 calls about children swallowing melatonin between 2012 and 2021, and the yearly count rose 530% over that decade (Report). Most of those calls were uneventful. About 88% were handled at home, and 83% of the children had no symptoms. Fewer than 2 in every 100 had a more serious outcome (Report). Two children under 2 died, though the researchers could not see enough records to say melatonin was the only cause. A later count estimated about 10,930 emergency visits among children aged 5 and under, and gummies were the form most often named (Report). Sweet, fruit-flavoured tablets belong in a closed cupboard.
A Melatonin Dosage That Works
Start with the smallest dose you can buy. That is usually 0.5 or 1 mg, and you can split a larger tablet. The range the trials support is roughly 0.5 to 3 mg, and the benefit stops climbing near 4 mg (Meta-analysis). Nothing in the research earns a 10 mg tablet.
Take it 2 to 3 hours before the bedtime you are aiming at, not as you climb into bed (Meta-analysis). That gap is the part doing the work.
Then protect the signal. Melatonin tells your body that it is dark, and bright light says the opposite. Dim the room and put the screen down.
Use it when your clock sits in the wrong place: a trip east, a run of night shifts, a bedtime that has drifted towards 3am. For a sleep problem that has lasted months, the therapy is the better bet (Guideline).
Read the label before you buy. Look for a third-party testing seal, and USP is the strictest (Advisory). Choose plain, fast-release tablets over gummies, which tested worst (Study). Ignore “extra strength”. Check whether the serving size is one unit or two.
Some people should ask a clinician first. That includes pregnancy or breastfeeding, melatonin meant for a child, anyone on prescription medicines, and poor sleep that has lasted months.
Frequently Asked Questions
What is the right melatonin dosage for sleep?
Most of the evidence points to a small dose. Pooled trial data show the benefit rising to about 4 mg and then levelling off, so 5 and 10 mg tablets sit past the useful range (Meta-analysis). In one small trial of older poor sleepers, 0.3 mg gave a better night than 3 mg (Trial). Starting at 0.5 to 1 mg is sensible, and bigger is not better.
How long before bed should I take melatonin?
Earlier than most people do. The 2024 analysis of 26 trials found the best results about 3 hours before the intended bedtime, rather than the usual 30 minutes (Meta-analysis). Clock-shifting studies agree, because melatonin taken at bedtime barely moves the body clock (Trial). Jet lag is the exception, since those trials dosed at bedtime on arrival (Systematic review).
Is it bad to take melatonin every night?
Trials have not turned up harm, and they have not shown much benefit from ongoing use either. A review searched 79 trials using 10 mg or more. The 4 trials solid enough to pool showed only minor complaints, such as drowsiness and headache (Meta-analysis). Long-term data are thin, so nightly use has never really been tested. Sleep specialists suggest against it as a standing treatment for chronic insomnia (Guideline).
Does melatonin stop your body making its own?
Trials have not reported that, and the safety review of high doses did not flag it (Meta-analysis). What does show up is leftover melatonin. A 3 mg dose kept melatonin in the blood well into the next day (Trial). Common 1 to 5 mg doses lift blood levels far above the natural night-time peak (Review).
Are melatonin gummies as good as tablets?
Probably not. Gummies tested worst for label accuracy, with 22 of 25 US products mislabelled (Study). They are also the form most often named when a small child swallows melatonin by accident (Report). A plain tablet is easier to split, which matters when the dose you want is under 1 mg.
Key Takeaways
- The benefit stops near 4 mg. In 26 pooled trials, sleep improved as the dose rose and then flattened at about 4 mg (Meta-analysis).
- When you take it matters too. The gap between the dose and sleep predicted how fast people dropped off, and about 3 hours worked best (Meta-analysis).
- Big doses look wasteful more than harmful. A review searched 79 trials of 10 mg or more, and the 4 it could pool showed only minor complaints (Meta-analysis).
- It suits clock problems best. Jet lag across five or more time zones is the strongest case (Systematic review), while sleep specialists suggest against it for chronic insomnia (Guideline).
- The label is often wrong. Measured content has run from 83% below to 478% above the printed dose (Study), so a tested brand is worth paying for.
Work With Your Clock
Melatonin nudges a clock. Once you see it that way, the choices get simpler. Keep the dose small, and put your effort into the hour you take it.
If your sleep problem is not a clock problem, look elsewhere. A steady sleep and wake time and morning light both do more for you. For insomnia that has lasted months, CBT-I is the first treatment to try.
A 1 mg tablet at 8pm looks like odd advice next to a 10 mg gummy at midnight. The trials keep pointing at the smaller, earlier one. Taking less and taking it sooner costs nothing to try, which is rare in this field.
This article is for educational purposes and is not medical advice. Talk to a qualified clinician before changing your health regimen.
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