Most adults need only 0.5 to 1 milligram of melatonin to improve sleep, though supplements commonly sold in stores range from 1 mg all the way up to 10 mg or more. That gap between what works and what’s on the shelf causes real confusion. Even a 0.5 mg dose creates melatonin levels higher than what your brain produces naturally to regulate your sleep-wake cycle, so more is rarely better.
Effective Doses for Adults
The European Food Safety Authority recommends 0.3 to 1 mg as the range needed to reduce the time it takes to fall asleep. A systematic review of studies in older adults found that doses from 0.5 to 6 mg improved sleep compared to a placebo, but doses above 6 mg showed no additional benefit. In the UK, where melatonin is a prescription medication, the standard dose is a 2 mg slow-release tablet taken 30 minutes to two hours before bedtime.
Starting low matters for a specific biological reason: taking too much can actually desensitize the receptors in your brain that respond to melatonin. When those receptors become less responsive, your natural sleep-wake cycle can get disrupted, and insomnia may worsen rather than improve. This is why sleep specialists consistently recommend beginning at 0.5 mg and only increasing if needed.
Doses for Children
There are no official dosage guidelines for children, which makes this trickier for parents. The American Academy of Pediatrics advises starting with the lowest possible dose and working with a pediatrician. Most children who benefit from melatonin, including those with ADHD or autism, don’t need more than 3 to 6 mg. Morning grogginess, headaches, and increased nighttime urination are the most common side effects in kids.
Safety is a real concern here. Between 2012 and 2021, poison control centers received more than 260,000 reports involving children and melatonin. Many of these cases happened because melatonin gummies look and taste like candy. If a child takes too much, symptoms typically include excessive sleepiness, bedwetting, dizziness, and nausea.
When to Take It
Timing depends on the type of sleep problem. For occasional insomnia, taking melatonin one to two hours before you want to fall asleep gives it time to signal your brain that nighttime is approaching. For ongoing sleep difficulties, a window of 30 minutes to one hour before bed is typical. For jet lag, take your first dose at the normal bedtime of your destination on the night you arrive.
Immediate-Release vs. Extended-Release
Melatonin supplements come in two main forms. Immediate-release tablets dissolve quickly and raise melatonin levels fast, which helps if your main problem is falling asleep. Extended-release tablets dissolve gradually over several hours, which helps more with staying asleep through the night. In one pharmacokinetic study, extended-release melatonin maintained effective sleep levels for a median of 6.7 hours, compared to 3.7 hours for immediate-release. If you wake up frequently in the middle of the night, the extended-release version is the better match.
Why Label Accuracy Is a Problem
In the United States, melatonin is classified as a dietary supplement, not a medication. That distinction has major practical consequences. The FDA does not test or approve melatonin products before they hit store shelves. Under current law, the burden falls on the FDA to prove a supplement is dangerous, rather than on the manufacturer to prove it’s safe and accurately labeled.
This regulatory gap means what’s on the label may not reflect what’s in the bottle. One study found that some products contained potentially dangerous amounts of melatonin, far exceeding what was listed. Others contained unexpected ingredients like serotonin or CBD. When you’re trying to take 0.5 mg and the actual content varies widely from product to product, precise dosing becomes nearly impossible. Choosing products that carry a third-party testing seal (such as USP or NSF) offers some assurance that the contents match the label.
Older Adults and Dose Adjustments
Older adults are often more sensitive to melatonin and may benefit from the lowest doses in the range. A review of evidence in this population found that 0.5 to 1 mg was enough to meaningfully reduce the time it takes to fall asleep. Because older adults metabolize supplements differently and are more likely to take other medications, lower doses also reduce the risk of next-day drowsiness and drug interactions. Doses above 6 mg provided no measurable improvement in sleep quality for this group.
Signs You’re Taking Too Much
If you’re experiencing grogginess that lasts well into the morning, vivid or disturbing dreams, headaches, or daytime drowsiness, your dose is likely too high. Some people also report mild nausea or dizziness. The counterintuitive pattern to watch for is worsening insomnia: if melatonin seemed to work at first but your sleep has gotten worse over time, receptor desensitization from a dose that’s too high could be the cause. Dropping down to 0.5 mg, or taking a break for a few nights, often helps reset things.