Melatonin isn’t just a sleep hack. It’s a key hormone that plays a central role in regulating your energy and circadian rhythm.

In the U.S., it’s sold in mega-doses of 10mg, no questions asked, and marketed as “safe and effective.” Kids’ versions come in fun fruit flavors.

In Europe, those same doses are prescription-only. Not because they don’t value their sleep; melatonin is not a vitamin, and the data behind it is more complicated than most labels suggest.

Melatonin doesn’t just affect sleep

Melatonin does more than make you drowsy, and in high doses, it can do more harm than good.

• Shifts puberty timing: Long-term use in children may disrupt the nighttime hormone cycles that trigger puberty onset.

• Metabolic effects: In a controlled clinical trial, healthy adults took 5mg of melatonin and showed impaired glucose tolerance: insulin secretion was reduced in the morning, and insulin sensitivity dropped in the evening.

• Hormonal changes in adults: Higher doses may influence reproductive hormones and thyroid activity.

These risks are amplified by the fact that most U.S. supplements contain unpredictable amounts of melatonin; anywhere from 74% to 347% of what’s on the label, and sometimes none at all.

Huberman on Melatonin

Neuroscientist Andrew Huberman has spoken extensively about melatonin; its benefits, limits, and risks. He describes it as a hormone that influences sleep, puberty timing, gonads, and bone mass. It can help initiate sleep, but those same pathways can disrupt hormone function if misused.

Huberman notes it doesn’t help maintain sleep and, in healthy adults, adds only ~3.9 minutes of total sleep and 2.2% efficiency. High supplemental doses can disrupt reproductive hormones, and in children may suppress puberty and impair bone development.

Why Europe classifies melatonin as a drug

Given these risks, it’s no surprise that Europe treats melatonin with far more caution. In the U.S., it’s categorized as a dietary supplement, meaning there’s little oversight of safety, manufacturing, or dosing.

• In Germany, melatonin is prescription-only for medicinal doses; only very low-dose supplements (<1mg) are sold OTC.

• In Italy, OTC use is allowed up to 1mg. 

• France allows doses under 2mg in food supplements, but warns against use in children, pregnant women, and those with autoimmune conditions.

Accidental ingestions in kids are rising

Between 2012 and 2021, melatonin became the most common substance involved in pediatric poison control calls in the U.S., with over 260,000 incidents and more than 4,000 hospitalizations, mostly in children under age 5.

The top form? Fruit-flavored gummies.

So should we stop taking melatonin?

Melatonin isn’t a poison, but it’s not a harmless vitamin either.

When to use: Short-term, like for jet lag or circadian rhythm shifts. For children, melatonin should be approached with extra caution, especially for long-term nightly use.

How much: The most studied, effective doses are very low (0.3–1 mg), far below the 5–10mg in most U.S. supplements…and work as well or better than higher doses, with fewer side effects. Doses above 5 mg offer no added benefit and more risk.

Who should avoid it: Routine nightly use in children, and anyone with certain hormonal conditions.

What to try instead: For sleep support without hormonal effects, experts often recommend magnesium threonate or bisglycinate, theanine, and apigenin.

Two kiwis before bed, or some tart cherry juice are also science-backed remedies for better sleep.

How to choose: If you do take melatonin, choose a third-party tested brand to avoid dose inconsistencies, and keep the dose tiny.

Europe restricts melatonin for the same reasons it restricts artificial dyes, seed oils in baby food, and ultra-processed additives: unclear long-term safety, inconsistent quality, and unnecessary exposure in vulnerable groups.

Meanwhile, in the U.S., melatonin is still sold in mega-doses, with minimal oversight and inconsistent quality control. We need more research and regulation on melatonin… not more gummy flavors.

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