Can’t sleep? When slumber doesn’t come naturally, some are turning to melatonin, an over-the-counter sleep aid that often is mistaken for a supplement. This powerful hormone plays an important role in human biology, and specialists are questioning whether increasing levels could be doing more harm than good.

A new investigation launched by the American Academy of Sleep Medicine is looking into the safety of melatonin. And while the health advisory checking the evidence is underway, the academy is recommending that melatonin not be used for insomnia in adults or children.

But what is insomnia, and how is it different from a few bad nights of sleep? Insomnia disturbs sleep at least three times a week for more than 3 months, often causing people to feel tired during the day as well.

Production of melatonin (dubbed the “vampire hormone”) begins at night, when it starts getting dark outside. Melatonin release is scheduled by the small but mighty pineal gland at the back of the head. Melatonin signals to the body that it’s time to sleep. And as the sun rises and light shines, melatonin levels decline again to help the body wake.

Sometimes packaged in gummy bear fruit flavors, melatonin can have an alluring appeal to sleep-deprived parents looking for relief for themselves and their children.

Muhammad Adeel Rishi, MD, vice chair of the Public Safety Committee for the American Academy of Sleep Medicine, says he has a doctor colleague who started taking melatonin to help him during the pandemic when he was having trouble falling asleep at night. His doctor friend started giving the hormone to his own children, who were also having sleep issues.

But Rishi says there are important reasons to not use melatonin for insomnia until more information is available.

Melatonin affects sleep, but this hormone also influences other functions in the body.

“It has an impact on body temperature, blood sugar, and even the tone of blood vessels,” Rishi says.

And because melatonin is available over the counter in the United States, it hasn’t been approved as a medicine under the FDA.

A previous study of melatonin products, for instance, flagged problems with inconsistent doses, which make it hard for people to know exactly how much they are getting and prompted calls for more FDA oversight.

Imprecise Doses

While melatonin doses typically range from 1 to 5 milligrams, bottles examined have been off target with much more or less hormone in the product than listed on the label.

Researchers from the University of Guelph in Ontario, Canada, tested 30 commercially available formulas and found the melatonin content varied from the ingredients labeled on the bottles by more than 10%.

In addition to melatonin, the researchers found other substances in the bottles too: In about a quarter of the products, they also identified another chemical messenger called serotonin.

Impurities

While melatonin plays a role in setting the body’s biological clock and the sleep and wake cycle, serotonin is also at work. Occurring naturally in our bodies, serotonin is involved in mood and helps with deep REM sleep. But adding serotonin in unknown amounts could be unhealthy.

Rishi says it can be dangerous to use a product as a medication when doses can be so off and there are unknown byproducts in it.

Serotonin can influence the heart, blood vessels, and brain, so it’s not something Rishi wants to see people taking without paying attention. People taking medication for mood disorders could be especially affected by the serotonin in their sleep aid, he warns.

For anyone taking melatonin, Rishi recommends they check the bottle to see whether they are using a product with a USP verified check mark, which indicates that the product meets the standards of the U.S. Pharmacopeia Convention.

The risk of impurities is a good reason for kids to not be given the hormone, but another worry is whether melatonin interferes with puberty in children – which is also a question researchers at the Children’s Hospital of Eastern Ontario in Ottawa, Canada, are asking.

Disrupting Puberty

While short-term melatonin use is considered safe, the researchers report, concerns that long-term use might delay children’s sexual maturation require more study. One theory is that nightly melatonin use might interrupt the decline of natural hormone levels and interfere with the start of puberty.

Researchers from the Children’s Hospital of Michigan in Detroit also reported an uptick in accidental ingestion of melatonin in children. Kids got their hands on melatonin and swallowed too many capsules more often than other pill-related mishaps during the pandemic, they reported in the journal Pediatrics.

Rishi says more research is needed to assess the safe use of melatonin in children. He points out that the hormone can treat circadian rhythm disorders in adults.

While specialists weigh the benefits and risks of melatonin use and where it is safest to try, Rishi says the hormone does have a role in medicine.

Melatonin will probably need to be regulated by the FDA as a medication – especially for children – Rishi points out. And what place, if any, it will have for managing chronic insomnia is “a big question mark.”

Results of the investigation by the American Academy of Sleep Medicine will be published on its sleepeducation.org website in a few months.