What is melatonin?

Melatonin is a hormone made from a pea-sized gland above the brain that helps your body know when to sleep and wake up. Your body produces more melatonin at night, as it gets darker, and levels drop to their lowest in the morning when the sun rises. You can also buy natural (made from animals) and synthetic melatonin in the form of gummies, drinks, and capsules, which cause drowsiness.

When taken correctly—on occasion, a couple of hours before bed—melatonin supplements can help you fall asleep. But a study published in the Journal of the American Medical Association (JAMA) in February 2022 says the “evidence supporting melatonin use for sleep disturbances is weak.” That doesn’t mean you need to stop taking it altogether, but it might help adjust your expectations of what melatonin can do.

What’s really in your melatonin supplement?

Because melatonin is considered a dietary supplement, not a drug, it isn’t tightly regulated by the Food and Drug Administration, and so the purity and ingredients vary widely. “The lack of detailed testing and regulation of supplements by the FDA is a widespread problem,” says Dr. Ana Krieger, medical director of the Center for Sleep Medicine at Weill Cornell Medicine and NewYork-Presbyterian. The JAMA study found the actual content of many melatonin products is up to 478% higher than what’s on the label. A typical melatonin dose is around 0.1 to 10 milligrams, which is already substantially higher than what your body produces—between 10 to 80 micrograms a night.

While it would be extremely rare to overdose on melatonin, taking too much can cause headaches, vomiting, and even changes in blood pressure. Furthermore, “not everyone tolerates melatonin, as it can lead to daytime fatigue, depressed mood, and residual drowsiness the next day—particularly if doses are higher than 3 milligrams,” says Krieger.

Additionally, some supplements may have other problematic ingredients. A 2017 study that tested 31 melatonin supplements sold at grocery stores and pharmacies found that 26% of them contained serotonin, another hormone that can cause harmful effects even in low doses. 

In other parts of the world, like the U.K. and most of Europe, melatonin is treated as a drug and would require a prescription. 

To ensure the safety of your supplement, Krieger suggests choosing only those that are certified by NSF International (formerly the National Sanitation Foundation), a third-party agency that verifies the purity of ingredients in supplements. 

Is it safe to take every night?

While melatonin is considered generally safe for short-term use, like occasional insomnia or getting over jet lag, many people take melatonin every night. That’s concerning if you consider that your nightly dose may be many times higher than what you intended or what the label promised. Experts caution that little is known about the effects of long term use of melatonin. If you’re regularly having trouble sleeping, talk to your doctor for advice—they may suggest other options, such magnesium and l-theanine, says Krieger. “As with any other sleep medications, the long-term use of supplements should be guided by a specialist,” she says. 

Address your sleep problems

A common misstep with melatonin is taking the supplement without fixing other sleep issues. “Relying on melatonin supplements alone without optimizing your nighttime habits, is often not the best approach,” says Krieger.

The best use of supplements is to enhance the benefits of a good nighttime routine, she says. That means ensuring your bedroom is dark (which encourages melatonin production), quiet, and cold. You should also go to bed and wake up around the same time, reduce exposure to bright light before bed, which suppresses the release of melatonin, and “[learn] how to reduce stressors and underlying anxieties that may be affecting sleep.”