Melatonin is a hormone your brain makes in the evening to tell your body that its getting closer to sleep time. In the US it is sold over the counter as a dietary supplement, and its use has exploded. Most people take it the wrong way, at the wrong time. The biggest harm so far has fallen on young children.

As a sleep physician, I hear about melatonin in almost every clinic visit. Patients either ask whether they should try it or are already taking it nightly. Very few understand why and how.

Why Melatonin Is Everywhere

A 2022 letter in JAMA tracked US adults over two decades. Regular melatonin use rose about 5x, from fewer than 1 in 200 adults around the year 2000 to roughly 1 in 50 by 2018. Sales followed the same path. According to the CDC, US melatonin sales nearly tripled between 2016 and 2020, reaching about $821 million a year.

Part of the reason is how melatonin is regulated. In many countries it requires a prescription. In the US it is classified as a dietary supplement, so it does not go through the FDA approval process that medicines do. Companies do not have to prove the dose on the label is accurate, and they do not have to use child-resistant packaging.

What Is Really in the Bottle

A 2023 study in JAMA tested 25 melatonin gummy products bought in the US. Most were mislabeled. The actual amount of melatonin ranged from about three quarters of the labeled dose to almost three and a half times the labeled dose. One product contained no melatonin at all. Some products labeled as containing CBD did contain it, which is a concern because CBD is not meant for children.

This means a parent who gives a child “1 mg” could be giving more than 3 mg without knowing it. Adults face the same problem.

If you do buy melatonin, look for the USP Verified mark on the label. It means an independent lab has checked that the product contains what it claims.

The Problem With Children

Melatonin is now one of the most common reasons parents call poison control. A 2022 CDC report found that pediatric melatonin ingestions reported to US poison centers rose by more than fivefold between 2012 and 2021. By 2021, melatonin accounted for about 1 in 20 of all pediatric poison center reports, up from fewer than 1 in 100 a decade earlier. Most cases were accidental ingestions in children age 5 and younger. Hospital stays and serious outcomes rose over the same period. Five children needed a breathing machine and two died.

A second CDC report found that melatonin led to about 11,000 emergency room visits for young children between 2019 and 2022. In about half the cases where the product was described, it was a gummy. Most of these children were not admitted to the hospital, but many had access to a whole bottle. In most cases the child got into a bottle that was not child-resistant or was left open.

Gummies look and taste like candy. Keep them up high, out of sight, and in a locked or child-resistant container. Treat them the same way you would treat any medicine.

How Melatonin Actually Works

Melatonin is not a sleeping pill. It does not knock you out. It works more like the dimming of a stage light that tells the actors the show is ending. Your brain starts releasing it a few hours before your natural bedtime, and that rising level signals your body clock to start winding down.

Because it acts as a timing signal, when you take it matters more than how much you take.

Most People Take It Too Late

Research suggests the benefit for falling asleep faster and sleeping longer peaks at around 4 mg a day, taken about 3 hours before your desired bedtime. Research shows that the most common real-world habit, a small dose taken 30 minutes before bed, gives less benefit.

In my practice, the most common pattern I hear is 5 to 15 mg taken about 30 minutes before bed. At that timing, melatonin has very little time to shift your body clock, and higher doses add side effects without adding much sleep.

For more on timing, see my post on Optimal Timing for Taking Melatonin.

Does It Help Insomnia?

For most people with long-term insomnia, not much, multiple studies have reiterated this.

Melatonin has a clearer role in body clock problems, such as jet lag, shift work, and delayed sleep phase, where a person’s natural sleep time runs very late. For chronic insomnia, cognitive behavioral therapy for insomnia (CBT-I) remains the first-line treatment because it addresses the habits and thought patterns that keep insomnia going.

Safety: What We Know and What We Don’t

Melatonin is often called “natural” and therefore safe. The truth is more mixed. Short-term use in adults appears fairly safe, but long-term safety has not been well studied.

Common side effects. A 2021 review in the Journal of Pineal Research looked at higher doses of 10 mg or more in adults. Melatonin did not raise the rate of serious side effects, but it did make daytime drowsiness, headache, and dizziness about 1.4 times as common as placebo.

Blood sugar. A 2026 randomized, studyl in the journal Diabetes Care gave healthy adults a single 5 mg dose of melatonin. In people who carry a common gene variant linked to type 2 diabetes, melatonin worsened glucose tolerance and blunted the body’s early insulin response. People without the variant were not affected. The study was small and short, but it supports advice not to eat large meals close to taking melatonin, especially if you have diabetes or prediabetes.

The heart. In 2025, a large health records study presented at the American Heart Association meeting linked long-term melatonin use to a higher rate of heart failure. It has not yet been published in full. A 2026 analysis in the journal Open Heart, using national survey data, found no link between melatonin use and heart disease or heart failure. Both studies were observational, and people who take melatonin often have poorer sleep, depression, or other health problems to begin with. Neither study proves harm or safety.

Other medicines. Melatonin can add to the effect of other sedating drugs and may interact with blood thinners, some blood pressure medicines, and certain antidepressants. If you take any prescription medicine, ask your doctor or pharmacist before starting melatonin.

Puberty. Natural melatonin levels fall as children move through puberty, and a 2025 review in the journal Psychoneuroendocrinology confirmed this pattern. This has raised concern that long-term melatonin use in children might affect the timing of puberty. So far that concern comes from biology rather than from human trials.

Who Should Be Careful

Children and teens should take melatonin only with guidance from their doctor, and only after sleep habits have been addressed first. Women who are pregnant, breastfeeding, or trying to conceive should also talk to their doctor first, since safety data in pregnancy are limited. The same applies to anyone with diabetes, a seizure disorder, or an autoimmune condition, and anyone taking blood thinners or blood pressure medicines.

DrSnoozz Says

Melatonin is a timing signal, not a sedative. Most people take too much, too close to bedtime, and get little benefit. US products often do not contain what the label says, and accidental ingestions in young children have risen sharply. Short-term use in adults looks fairly safe, but long-term effects on blood sugar, the heart, and children’s development are still not well understood. Use it for the right problem, at the right time, at a modest dose, and with your doctor’s input, especially for children, teens, and women of reproductive age.

Disclaimer

This article is for general education only and is not medical advice. It does not replace an evaluation by a qualified healthcare provider. Talk with your doctor or a board-certified sleep medicine specialist before starting, stopping, or changing any supplement or medicine, and before giving melatonin to a child.

---

References

1. Andersen, C. C., Kjær, E. K. R., Vase, C. B., Mathiasen, R., Debes, N. M., Jørgensen, N. R., & Jennum, P. J. (2025). Melatonin secretion across puberty: A systematic review and meta-analysis. Psychoneuroendocrinology, 173, 107281.
2. Cohen, P. A., Avula, B., Wang, Y.-H., Katragunta, K., & Khan, I. (2023). Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA, 329(16), 1401-1402.
3. Cruz-Sanabria, F., Bruno, S., Crippa, A., Frumento, P., Scarselli, M., Skene, D. J., & Faraguna, U. (2024). Optimizing the time and dose of melatonin as a sleep-promoting drug: A systematic review of randomized controlled trials and dose-response meta-analysis. Journal of Pineal Research, 76(5), e12985.
4. De Crescenzo, F., D’Alò, G. L., Ostinelli, E. G., Ciabattini, M., Di Franco, V., Watanabe, N., Kurtulmus, A., Tomlinson, A., Mitrova, Z., Foti, F., Del Giovane, C., Quested, D. J., Cowen, P. J., Barbui, C., Amato, L., Efthimiou, O., & Cipriani, A. (2022). Comparative effects of pharmacological interventions for the acute and long-term management of insomnia disorder in adults: A systematic review and network meta-analysis. The Lancet, 400(10347), 170-184.
5. Freeman, D. I., Lind, J. N., Weidle, N. J., Geller, A. I., Stone, N. D., & Lovegrove, M. C. (2024). Notes from the field: Emergency department visits for unsupervised pediatric melatonin ingestion, United States, 2019-2022. MMWR. Morbidity and Mortality Weekly Report, 73(9), 215-217.
6. Khan, B., & Lima, B. B. (2026). Melatonin and cardiovascular risk: An NHANES reality check after recent heart failure concerns. Open Heart, 13(1).
7. Lelak, K., Vohra, V., Neuman, M. I., Toce, M. S., & Sethuraman, U. (2022). Pediatric melatonin ingestions, United States, 2012-2021. MMWR. Morbidity and Mortality Weekly Report, 71(22), 725-729.
8. Li, J., Somers, V. K., Xu, H., Lopez-Jimenez, F., & Covassin, N. (2022). Trends in use of melatonin supplements among US adults, 1999-2018. JAMA, 327(5), 483-485.
9. Menczel Schrire, Z., Phillips, C. L., Chapman, J. L., Duffy, S. L., Wong, G., D’Rozario, A. L., Comas, M., Raisin, I., Saini, B., Gordon, C. J., McKinnon, A. C., Naismith, S. L., Marshall, N. S., Grunstein, R. R., & Hoyos, C. M. (2022). Safety of higher doses of melatonin in adults: A systematic review and meta-analysis. Journal of Pineal Research, 72(2), e12782.
10. Qian, J., Stefanovski, D., Andersen, P. A. K., Vujovic, N., Kelly, L., Lepson, J., Nguyen, H., Byrne, S., Wang, W., Mandrup-Poulsen, T., Adler, G., Garaulet, M., Saxena, R., & Scheer, F. A. J. L. (2026). Melatonin impairs glucose tolerance, first-phase insulin secretion, and insulin feedback inhibition: Interaction with MTNR1B diabetes risk variant. Diabetes Care, 49(8), 1498-1506.
11. Wasey, W. (@dr.snoozz). (2026). Optimal timing for taking melatonin [Instagram post]. Instagram.