Melatonin helps some sleep problems and not others, and the difference comes down to what it actually is. Melatonin is a hormone your body releases in response to darkness to signal that it's night, which makes it a timing cue rather than a sedative. It's genuinely effective for jet lag and for sleep schedules that have drifted out of alignment. For ordinary chronic insomnia in adults, the evidence is weak enough that the American Academy of Sleep Medicine recommends against using it.
That gap between reputation and evidence is worth understanding, because melatonin use among US adults has roughly quintupled over the past two decades. This guide covers what the research actually shows, how much to take (less than most bottles contain), when to take it, the side effects, and two safety issues that get very little attention: what's really inside these products, and what's been happening to children.
What is melatonin and how does it work?
Melatonin is a hormone produced mainly by the pineal gland in your brain, released in response to darkness. Its job is to tell your body what time it is, not to force you unconscious.
The timing detail matters more than most people realize. Your natural melatonin starts rising in the early evening, and that rise essentially sends a message that sleep should happen in roughly three hours. It's an opening announcement, not a switch. That's why swallowing a large dose at bedtime and expecting to be knocked out misunderstands the mechanism, and why melatonin performs so much better at moving your body clock than at forcing sleep on a clock that isn't ready.
Does melatonin actually work? What the research shows
The honest answer depends entirely on why you can't sleep.
For chronic insomnia in adults, the evidence doesn't support it. The American Academy of Sleep Medicine's clinical practice guideline states plainly that clinicians should not use melatonin as a treatment for either sleep onset or sleep maintenance insomnia in adults. The American College of Physicians reached a similar conclusion, finding insufficient evidence and small effect sizes, and a 2020 VA and Department of Defense guideline described the clinical significance of the minimal improvements as unclear. European guidelines also do not recommend it.
The numbers explain why. Even in studies that found a positive effect, melatonin shortened the time to fall asleep by roughly 6 to 10 minutes. A 2022 meta-analysis in Sleep Medicine Reviews found that in adults with insomnia not linked to another condition, melatonin produced no significant improvement in how quickly they fell asleep, how long they slept, or their sleep efficiency.
For children and adolescents, the picture is different. That same meta-analysis found melatonin significantly improved both sleep onset and total sleep time in children and teens, and it's used under clinical supervision for sleep-onset problems in children with certain neurodevelopmental conditions.
For jet lag, it works. This is where melatonin has its strongest evidence. A Cochrane review found that 8 of 10 trials showed a benefit for jet lag. Notably, doses between 0.5 and 5 mg were equally effective, meaning a larger dose bought no additional benefit.
For a delayed body clock, it works. If you're a night owl whose sleep has shifted hours later than you want, melatonin can help pull it back. This is the circadian use the AASM addresses in a separate guideline on circadian rhythm sleep-wake disorders, and it's a different question from treating insomnia.
For older adults with trouble falling asleep, it may modestly help. One trial in older adults found reductions in time-to-sleep of roughly 19 minutes at three weeks and 26 minutes at 19 weeks. It is not, however, indicated for sleep maintenance problems, meaning waking repeatedly in the night or too early in the morning.
The overall shape is consistent: melatonin helps when the problem is timing, and does little when the problem is insomnia itself.
How much melatonin should you take?
Probably far less than the bottle in your cabinet contains. Research suggests that a dose of about 0.3 to 0.5 mg matches the body's natural levels and works about as well as 3 to 10 mg for most purposes. A 2024 dose-response meta-analysis modeled efficacy peaking around 4 mg per day, with 3 to 4 mg outperforming 2 mg. Either way, both figures sit well below the 5 mg and 10 mg products that dominate store shelves.
The Cochrane jet lag finding makes the point most clearly: between 0.5 and 5 mg, larger doses were not more effective. Taking more melatonin doesn't produce more sleep; past a certain point it mostly produces more side effects and a groggier morning.
UC Davis Health suggests a conservative approach for adults of starting at around 1 mg and only increasing gradually if needed. For children, the same source suggests starting far lower, around 0.25 to 0.5 mg, and stresses talking to a pediatrician first. Children under 2 should not be given melatonin at all.
Because appropriate use depends on your situation, medications, and what's actually causing your sleep problem, treat these as what the research and clinicians describe rather than a personal prescription, and check with a doctor or pharmacist before starting, especially for a child.
When should you take melatonin?
Timing may matter as much as dose. The 2024 dose-response meta-analysis found that the interval between taking melatonin and the intended sleep period significantly predicted how well it worked.
For general sleep-onset help, melatonin is typically taken about 30 to 90 minutes before your target bedtime. For shifting a delayed body clock earlier, it's usually taken considerably earlier, often around three hours before your target bedtime, which mimics the natural evening rise. That's a meaningful distinction: for circadian shifting, taking it at bedtime is roughly the wrong time.
If you're using it to reset a schedule rather than to feel sleepy tonight, our guide on how to fix your sleep schedule covers how melatonin fits alongside the more powerful lever, which is light.
Side effects and safety
Melatonin is generally well tolerated, and its safety profile is genuinely reassuring in some important respects. Evidence indicates no tolerance or dependence even after 12 months of continuous use, no withdrawal symptoms or rebound insomnia when you stop, and no suppression of your body's own melatonin production. Those are the three things people most often worry about, and the evidence doesn't support them.
The most common side effects are daytime drowsiness, headache, dizziness, and nausea. Mayo Clinic also lists less common effects including short-lasting feelings of depression, mild tremor, mild anxiety, abdominal cramps, irritability, reduced alertness, and confusion or disorientation.
A few groups need more caution. Older adults may be more sensitive to dizziness and drowsiness, and melatonin can stay in the body longer with age, increasing the chance of next-day grogginess; the AASM does not recommend melatonin for sleep problems in people with dementia. For pregnancy and breastfeeding, it simply isn't known whether melatonin is safe, so it shouldn't be used without medical advice.
The problem nobody mentions: what's actually in the bottle
Here's the issue that undercuts every dosing discussion. In the United States, melatonin is sold as a dietary supplement, which means it isn't held to the manufacturing standards that apply to medicines.
A 2023 analysis published in JAMA tested 25 melatonin gummy products and found that 22 of them, or 88%, were inaccurately labeled. Only three products contained an amount within 10% of what the label declared. The actual melatonin content ranged from 74% to 347% of the stated amount, and one product contained no detectable melatonin at all, though it did contain 31.3 mg of CBD.
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The practical implication is uncomfortable: if you take a “3 mg” gummy, you may be getting anywhere from about 2 mg to over 10 mg, and you have no way to know which. As a Mayo Clinic researcher commenting on the study put it, the findings call into question the confidence patients and providers can have in these products. If you do use melatonin, look for third-party verification such as USP or NSF certification, which at least indicates the contents have been independently tested.
Melatonin and children: what parents should know
This deserves its own section, because the trend is stark. According to CDC data published in 2022, calls to US poison control centers for pediatric melatonin ingestions rose 530% between 2012 and 2021. Those calls were associated with 27,795 emergency department and clinic visits, 4,097 hospitalizations, and 287 intensive care unit admissions. Two deaths occurred among the reported cases, though these were not attributed solely to melatonin.
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The pattern behind those numbers is mundane and preventable. Roughly 85% of the calls involve children aged 5 or younger, typically finding a parent's supply and mistaking it for candy, which is exactly what many gummy products resemble. Federal rules don't require child-resistant packaging on supplements the way they do for medicines.
If a child does swallow melatonin, drowsiness usually appears within an hour, and gummies may cause nausea or an upset stomach. Poison control guidance is to monitor breathing and responsiveness, never to force vomiting, and to call 911 if the child struggles to breathe or can't be woken. Keep supplements stored out of reach and out of sight, and treat them like medication rather than a bedtime treat.
None of this means melatonin is dangerous for children under medical supervision, where it has legitimate uses. It means unsupervised access and unpredictable dosing are the actual risks.
What works better for insomnia
If your problem is genuine insomnia, the treatment with the strongest evidence isn't a supplement at all. Cognitive behavioral therapy for insomnia, or CBT-I, is the first-line treatment recommended by both US and European guidelines. A network meta-analysis comparing melatonin, light therapy, exercise, and various complementary approaches found that none had evidence superior to CBT-I.
Alongside that, the behavioral fundamentals do more than most supplements: a consistent wake time, bright light in the morning, a dark and screen-free evening, and keeping caffeine to the first half of the day. Our guides on improving sleep quality and sleeping better at night cover these in detail. If you've been sleeping badly at least three nights a week for three months or more, that's a conversation to have with a doctor rather than a problem to solve in the supplement aisle.
Frequently asked questions
How long does melatonin take to work?
Most people notice drowsiness within about an hour, which is why it's typically taken 30 to 90 minutes before bed. If you're using it to shift a delayed sleep schedule rather than to feel sleepy tonight, it's usually taken earlier, around three hours before your target bedtime, and the effect on your body clock builds over days rather than appearing in one night.
Is 10 mg of melatonin too much?
It's more than the evidence supports for most people. Research indicates that doses around 0.3 to 0.5 mg match natural physiological levels, and a dose-response analysis found efficacy peaking near 4 mg, so 10 mg is well past the point of added benefit. For jet lag, doses from 0.5 to 5 mg worked equally well. Higher doses mainly increase the likelihood of grogginess and other side effects.
Can you overdose on melatonin?
Serious overdose in healthy adults is uncommon, and melatonin doesn't cause dependence or withdrawal. The real-world risk sits with children, where unsupervised ingestion has driven a large rise in poison control calls, emergency visits, and hospitalizations. If a child has taken melatonin and is unusually difficult to wake or is having trouble breathing, call emergency services; otherwise contact poison control for guidance.
Is melatonin safe to take every night?
For most healthy adults, short-term nightly use appears well tolerated, and evidence indicates no tolerance, dependence, or suppression of natural production even over 12 months. That said, long-term data is limited, and nightly reliance often signals an underlying sleep problem that deserves proper attention rather than indefinite supplementation. If you can't sleep without it, that's worth raising with a doctor.
Does melatonin help you stay asleep?
Generally no. Melatonin's evidence is around falling asleep and shifting sleep timing, not maintaining sleep, and it isn't indicated for people whose main problem is waking repeatedly in the night or too early in the morning. Frequent night waking is worth investigating for other causes, including sleep apnea and insomnia.
The fairest summary is that melatonin is a useful tool aimed at the wrong problem by most of the people taking it. If you're crossing time zones or trying to drag a delayed body clock earlier, it genuinely helps, at a smaller dose and an earlier hour than most people use. If you're lying awake night after night, the evidence points firmly toward CBT-I and your sleep habits instead. And whatever you take, buy third-party tested products and keep them well out of reach of children.
