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Melatonin supplement use jumped dramatically in the past 2 decades, researchers found.

Among U.S. adults, melatonin supplement consumption significantly increased from 1999-2000 to 2017-2018 across all demographic groups, reported Naima Covassin, PhD, of the Mayo Clinic in Rochester, Minnesota, and co-authors in a

Melatonin use rose from 0.4% in 1999-2000 to 2.1% in 2017-2018, which corresponded to over 6 million people, the researchers said. The most notable increase was in the last decade, and the prevalence of using higher-dose melatonin (over 5 mg/day) was greater with time.

The findings may raise safety concerns, especially since the actual content of melatonin supplements may be than the labeled content, the researchers noted.

"Given the increasing popularity in use of exogenous melatonin, our observations support the need for better awareness of safety and effects of melatonin supplements in the public, as well as among medical professionals," Covassin told 乌鸦传媒.

"Indeed, while melatonin is effective in resetting our circadian clock, and therefore primarily indicated for , it has been widely adopted as a non-prescription therapy for sleep promotion," Covassin said. But the extensive variety of formulations, doses, routes, and timing of supplemental melatonin has meant there's not much evidence about its clinical efficacy as a sleep aid, she maintained.

Because melatonin is sold as a dietary supplement, it's not subject to the same regulations and standards applied to drugs, Covassin pointed out. "Therefore, the quality, purity, and dose accuracy of melatonin supplements may not be adequately controlled," she said.

"Additionally, despite being generally considered safe and well-tolerated, side effects following melatonin supplementation have been reported, especially at high doses and in patients with pre-existing vulnerabilities, and long-term safety data are scarce," she added.

"There's actually a lot of evidence to show that melatonin can help people fall asleep faster and have better sleep quality, and it may be even more beneficial for jet lag and addressing sleep timing problems," observed Michael Grandner, PhD, of the University of Arizona in Tucson, who wasn't involved with the study. "Accumulating evidence also shows that, in certain doses, it can support a healthy immune system."

"However, many people don't really use it correctly," Grandner told 乌鸦传媒. "It does not generally work to treat insomnia and the dose and timing can be tricky to get right. For example, higher doses are not necessarily more effective."

The study used data from the 1999-2000 through 2017-2018 cycles of the CDC's National Health and Nutrition Examination Survey ( for people ages 20 and older to examine melatonin trends. "Because the recommended dosage of melatonin typically does not exceed 5 mg/d, we additionally evaluated prevalence and trends in use of greater than 5 mg/d of melatonin," the researchers noted.

Data from 55,021 adults from 10 NHANES cycles were included in the analysis. Mean age of participants was 47.5, and 52% were women.

The overall weighted prevalence of melatonin use rose from 0.4% (95% CI 0.2%-1.0%) in 1999-2000 to 2.1% (95% CI 1.5%-2.9%) in 2017-2018 (P=0.004), with an increase starting in 2009-2010. Trends were similar for both men and women and across age groups.

Before 2005-2006, melatonin use exceeding 5 mg/day was not reported. The prevalence of melatonin use greater than 5 mg/day increased from 0.08% (95% CI 0.02%-0.38%) in 2005-2006 to 0.28% (95% CI 0.13%-0.60%) in 2017-2018 (P=0.005), the researchers found.

The study's limitations included its reliance on self-reported melatonin use, although supplement containers were verified in nearly all participants, Covassin and colleagues said. In some subgroups, the number of melatonin users was small and stratified data should be interpreted with caution, they acknowledged. "Reliable estimates of trends in melatonin use across racial/ethnic groups cannot be provided," they added.

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