For most adults, anything above 5 mg of melatonin is more than your body needs, and doses above 10 mg are widely considered excessive. Your body naturally produces less than 0.1 mg of melatonin per night, so even a standard 3 mg supplement already floods your system with far more than it would ever make on its own. The sweet spot for most people is between 0.5 mg and 3 mg, taken one to two hours before bed.
What Counts as a Normal Dose
For short-term insomnia, a typical starting dose is 2 mg of slow-release melatonin taken one to two hours before bedtime. For longer-term sleep problems, doses may gradually increase under medical guidance, but the ceiling is generally 10 mg per day. For jet lag, 3 mg is standard, with a maximum of 6 mg.
Children respond to much lower amounts. Most kids who benefit from melatonin do well on 0.5 mg to 1 mg, and even children with ADHD or other conditions that disrupt sleep rarely need more than 3 to 6 mg. The American Academy of Pediatrics recommends starting at the lowest possible dose and using it for short stretches, since the long-term effects on growth and development, particularly during puberty, aren’t well understood.
Why More Doesn’t Mean Better
Taking a high dose of melatonin can actually backfire. When your body’s melatonin receptors are exposed to levels far above what they’d encounter naturally, they become less responsive. Lab research has shown that prolonged exposure to high concentrations of melatonin desensitizes the main sleep-related receptor, reducing its ability to respond to the hormone. Normal nighttime levels of melatonin don’t cause this effect. Only the supraphysiological levels created by large supplement doses do.
In practical terms, this means that taking 10 mg when 1 mg would work can make melatonin less effective over time. Some people who feel melatonin “stopped working” have simply pushed their receptors into a desensitized state. Scaling back to a lower dose, sometimes as little as 0.5 mg, often restores the effect.
Side Effects of Taking Too Much
Melatonin is not acutely dangerous in the way that many other sleep aids are. There is no well-established lethal dose, and poison control data doesn’t point to a clear toxicity threshold. But higher doses reliably produce more side effects, including:
- Next-day grogginess and daytime sleepiness
- Headaches
- Nausea or stomach pain
- Dizziness
- Vivid or strange dreams and night sweats
- Irritability or restlessness
- Dry mouth and itchy skin
In children, the most commonly reported symptoms after taking too much include sleepiness, bedwetting, headache, dizziness, and nausea. If your child accidentally takes a large amount, contact Poison Control for guidance.
The Label Problem
One reason people accidentally take too much is that melatonin supplements often contain far more (or less) than what’s printed on the label. A study analyzing 31 melatonin products found that the actual melatonin content varied dramatically from what was advertised, with lot-to-lot variability within a single product ranging by as much as 465 percent. That means a pill labeled 3 mg could contain anywhere from a fraction of a milligram to well over 10 mg.
The same analysis found serotonin, a completely different and more tightly regulated compound, in 26 percent of the supplements tested. Because melatonin is sold as a dietary supplement in the United States rather than a regulated medication, there’s no guarantee of purity or dosage accuracy. Choosing products that carry a third-party testing seal (like USP or NSF) helps reduce this risk.
Who Needs to Be Extra Careful
Melatonin can interact with several categories of medication. It may increase bleeding risk if you’re taking blood thinners or anti-platelet drugs. It can also affect blood sugar levels, which matters if you’re managing diabetes with medication. If either applies to you, the dose that’s “too much” may be lower than for someone not taking those drugs.
Older adults metabolize melatonin more slowly, which means a given dose produces higher and longer-lasting blood levels than it would in a younger person. Starting at 0.5 to 1 mg is a reasonable approach for anyone over 65. One large study of Medicare patients found that sleep medications broadly increase the risk of falls, fractures, and other serious accidents in this age group, so keeping the dose minimal matters.
How to Find Your Right Dose
Start at the lowest dose available, ideally 0.5 mg or 1 mg. Take it 30 to 90 minutes before you want to fall asleep. If that works, there’s no reason to increase it. If it doesn’t help after a week, you can try stepping up to 2 or 3 mg, but resist the urge to jump to 5 or 10 mg. Higher doses don’t produce proportionally better sleep. They mostly just produce more side effects and receptor desensitization.
Timing matters as much as dose. Melatonin signals to your brain that it’s nighttime. Taking it too early in the evening or too close to when you want to wake up can shift your sleep cycle in the wrong direction. For standard insomnia, one to two hours before bed is the usual window. For jet lag, take it at the bedtime of your destination time zone.
If you’ve been taking a high dose for a while and want to scale back, you can reduce gradually over a week or two. There’s no physical withdrawal from melatonin, but your sleep may be temporarily disrupted as your body readjusts. Most people find that a lower dose works just as well, or better, once their receptors recover sensitivity.