Melatonin: What the Evidence Says and How to Use It Safely

What melatonin is

Your pineal gland releases melatonin in the evening as darkness falls, and levels stay high through the night. It does not force sleep the way a sedative does. Instead, it tells your body clock that it is night. That is why it is more useful for timing problems, like jet lag or a delayed sleep schedule, than for general insomnia.

Where the evidence is stronger

• Jet lag: research suggests melatonin can reduce jet lag symptoms, especially when flying east across several time zones.
• Delayed sleep-wake phase disorder: the AASM's guideline on circadian rhythm sleep disorders supports strategically timed melatonin for this condition, in which people cannot fall asleep until very late.
• Some children with autism or ADHD-related sleep problems, under a doctor's supervision.

For chronic insomnia in adults, the AASM's 2017 pharmacologic guideline suggested against using melatonin, because the improvement in sleep was small.

Timing matters more than dose

To shift your clock earlier, melatonin is typically taken a few hours before your desired bedtime, not at the moment you get into bed. Research studies have used a wide range of doses, commonly 0.5 mg to 5 mg, and higher doses are not necessarily more effective. Larger amounts can cause next-day grogginess. Ask a pharmacist or doctor how to time it for your situation.

US products are inconsistent

In the US, melatonin is regulated as a dietary supplement, not a drug, so products are not checked by the FDA for content before sale. A 2023 study in JAMA tested 25 melatonin gummy products: the measured melatonin ranged from 74% to 347% of the labelled amount, and only 3 were within 10% of the label. Some also contained CBD. An earlier study of supplements in Canada found contents ranging from 83% less to 478% more than labelled.

If you use melatonin, choose a product with third-party verification (such as a USP Verified mark), which tests that the product contains what it says. In the UK and many other countries, melatonin is available only by prescription.

Children and melatonin

The AASM issued a health advisory in 2022 urging parents to talk to a healthcare professional before giving melatonin to children. A CDC report found that pediatric melatonin ingestions reported to US poison control centers rose by 530% between 2012 and 2021, mostly accidental ingestions by children aged 5 and under. Store melatonin like medicine, out of reach, especially gummies that look like candy. Behavioral approaches such as consistent routines are recommended first for children's sleep problems.

Side effects and who should check first

Short-term use appears to be safe for most adults. Possible side effects include headache, dizziness, nausea and daytime sleepiness. Check with a doctor or pharmacist before using melatonin if you are pregnant or breastfeeding, have an autoimmune condition, epilepsy or depression, or take blood thinners, diabetes medications, immunosuppressants, sedatives or other medications. Long-term safety has not been well studied.

The bottom line

Melatonin can be a useful tool for jet lag and body clock timing problems. It is not a strong sleeping pill, and if you are relying on it nightly for insomnia, a clinician can help you explore CBT-I and look for underlying causes.