OTC Melatonin Supplement Use Rises Fivefold Over 20 Years: Study

Randy Dotinga

February 01, 2022

The use of over-the-counter melatonin supplements grew by fivefold over the past two decades in the United States, a new study finds, although only 2% of a recent group of survey respondents said they had taken the sleep aid within the past month.

The findings, reported today in a research letter in the Journal of the American Medical Association, suggest that "millions of US individuals are using melatonin," study co-author Naima Covassin, PhD, an associate consultant at Mayo Clinic in Rochester, Minnesota, told Medscape Medical News. "It is important to ask patients who report sleep problems whether they consume melatonin supplements, and these findings should certainly prompt more research in this area."

The supplements boost the levels of melatonin, a hormone that is linked to the sleep–wake cycle. "Melatonin facilitates our ability to fall asleep at our bedtime by decreasing the natural early evening circadian arousal that helps keep us alert despite our having been awake since the morning," said David Neubauer, MD, a sleep specialist at Johns Hopkins University School of Medicine, Baltimore, Maryland. "It isn't so much that melatonin is sedating, but rather that it turns off arousal."

For the new study, researchers tracked data from the National Health and Nutrition Examination Survey from 1999-2000 to 2017-2018 and focused on respondents aged 20 and older (n = 55,021, mean age, 47.5, 52% women). As the researchers noted, response rates dipped mightily from a high of 84% in 2001-2002 to just 51.9% in 2017-2018.

The study found that the overall reported weighted prevalence of melatonin use grew from 0.4% (95% CI, 0.2% - 1.0%) in 1999-2000 to 2.1% (95% CI, 1.5% - 2.9%) in 2017-2018 (linear P = .004). In 93.9% of cases of reported melatonin use, the surveyors confirmed it by checking for supplement bottles.

"These trends were similar in men and women and across age groups," Covassin said. "We also found that use of more than 5 mg/day melatonin was not reported till 2005-2006, and it has been increasing since."

Melatonin supplements are now available in tablets, capsules, gummies, powders, liquids, sprays, and other formulations. Users can even buy CBD-melatonin combos.

The survey doesn't explore why the survey respondents used melatonin nor whether they thought it actually helped them. "The study was designed to evaluate the breadth of use of melatonin, rather than its effectiveness as a sleep aid," Covassin said.

Neubauer, who wasn't associated with the study, said the research seems valid. According to him, melatonin use has likely grown due to marketing and a higher number of products. He added that melatonin products are being manufactured at higher doses, although melatonin has a flat dose-response curve. "Higher doses typically do not have a greater effect," he said.

According to Covassin, melatonin is generally considered to be safe, although side effects such as fatigue, dizziness, and headaches have been reported in clinical trials. "This is especially evident when high doses are administered," Covassin said. "Other potentially more harmful consequences have also been noted. For instance, it has been found that acute administration of melatonin may decrease glucose tolerance, which may be especially problematic in patients with preexisting vulnerabilities such in those with diabetes. There are also very limited data on whether sustained use is safe in the long run."

Moving forward, Covassin said, "we are interested in better understanding consumption of melatonin supplements across different populations as well as the impact of chronic use."

The study authors are supported by grants from the National Natural Science Foundation of China, National Institutes of Health, Sleep Number Corporation (to Mayo Clinic), the Alice Sheets Marriott Professorship, and the Mayo Clinic Marie Ingalls Research Career Development Award.

Covassin and Neubauer have disclosed no relevant financial relationships. Study co-author Virend K. Somers, MD, PhD, reports having served as a consultant for Respicardia, Baker Tilly, Bayer, and Jazz Pharmaceuticals and serving on the Sleep Number Research Advisory Board. 

JAMA. Published online February 1, 2022. Research Letter

Randy Dotinga is a freelance journalist who covers medicine and health.

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