Most adults get the best results from melatonin at doses between 0.5 and 5 mg, taken before bedtime. There is no officially established maximum safe limit, but clinical guidelines cap prescribed doses at 10 mg per day for adults with ongoing sleep problems. Starting low, at 0.5 to 1 mg, is more effective than most people expect, and higher doses don’t necessarily work better.
Effective Doses for Adults
For short-term insomnia, the NHS recommends a standard dose of 2 mg in a slow-release tablet, taken one to two hours before bed. For longer-term sleep problems, the starting dose is the same 2 mg, but it can be gradually increased up to 10 mg if needed. That 10 mg ceiling represents the highest dose used in routine clinical practice.
What surprises many people is how little melatonin you actually need. The European Food Safety Authority found that doses as low as 0.3 to 1 mg reliably reduce the time it takes to fall asleep. Your body naturally produces melatonin in tiny amounts to signal darkness to your brain, so even a fraction of a milligram can meaningfully shift that signal. Doses of 5 or 10 mg don’t put you to sleep faster the way a higher dose of a painkiller reduces more pain. Melatonin works as a timing cue, not a sedative, so more is not necessarily more effective.
Doses for Children
Children respond to even smaller amounts. The American Academy of Pediatrics recommends starting at 0.5 to 1 mg, given 30 to 90 minutes before bedtime. Most children who benefit from melatonin, including those with ADHD, don’t need more than 3 to 6 mg. Because melatonin is sold as a supplement in most countries, it’s easy to accidentally give a child an adult-strength gummy or tablet, so checking the label carefully matters.
Doses for Older Adults
Adults over 65 tend to clear melatonin from their bodies more slowly, which means a given dose lingers longer and has a stronger effect. 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. Starting at the low end (0.5 to 1 mg) is the safest approach, especially for anyone already taking other medications that cause drowsiness. Higher doses in this age group can sometimes worsen sleep quality rather than improve it.
What Happens If You Take Too Much
Melatonin has a remarkably wide safety margin compared to prescription sleep aids. Poison Control reports that even large accidental doses don’t cause serious toxicity. In documented cases, a two-year-old who swallowed up to 138 mg slept for a couple of hours and was then fine. A 50-year-old woman who intentionally took 100 mg experienced about 12 hours of drowsiness and a temporarily elevated heart rate, but nothing more severe.
Common symptoms of taking too much include excessive sleepiness, headache, nausea, and sometimes irritability or agitation. There is no antidote for a melatonin overdose because one isn’t needed. The body processes it and moves on. That said, routinely taking high doses (20, 30, or 50 mg) has no proven benefit and can leave you groggy, give you vivid dreams, or disrupt your sleep cycle in the opposite direction.
Why Your Pill May Not Contain What It Says
One complication worth knowing about: melatonin supplements are poorly regulated in the United States. A study published by researchers and highlighted by the American Academy of Sleep Medicine tested 31 melatonin products and found that over 71 percent contained an amount that didn’t match the label, even allowing a generous 10 percent margin of error. Actual melatonin content ranged from 83 percent less than what was listed to 478 percent more. Even different bottles of the same brand varied by as much as 465 percent between production lots.
This means a pill labeled “3 mg” could contain anywhere from roughly 0.5 mg to over 14 mg. If you’ve tried melatonin before and found it didn’t work or made you feel terrible, inconsistent dosing could be the reason. Choosing products with a third-party testing seal (USP, NSF, or ConsumerLab) gives you more confidence in what you’re actually swallowing.
Timing Matters as Much as Dose
Taking melatonin right as you climb into bed is the most common mistake. Because it works by shifting your internal clock rather than knocking you out, the timing window matters. For general sleep support, taking it one to two hours before your target bedtime works well. Some research suggests that taking it three to four hours before you want to sleep is even more effective at aligning your circadian rhythm, particularly if you tend to feel alert late into the evening.
For people with delayed sleep phase syndrome, where the body’s natural sleep window is shifted hours later than desired, the approach is different. A low dose of 0.5 to 1 mg taken a full four hours before the desired bedtime can gradually pull the sleep window earlier. This is not a bedtime medication in that context. It’s a clock-resetting tool, and the earlier timing is what makes it work.
Long-Term Use
Melatonin is generally considered safe for short-term use, spanning a few weeks to a couple of months. The evidence on long-term daily use is thinner. The Mayo Clinic notes that more research is needed to understand what happens with years of nightly supplementation. Unlike many prescription sleep medications, melatonin does not appear to cause physical dependence or withdrawal symptoms, and your body doesn’t seem to build tolerance to it in the way it does with other sleep aids. Still, if you find yourself relying on it every night for months, the underlying cause of your sleep trouble is worth investigating rather than simply increasing the dose.