Melatonin in sleep-aid gummies can be off by up to 350%, study finds

An eye-opening analysis of common over-the-counter sleep aids finds they contain wildly variable amounts of melatonin, with some packing up to 347 percent of the amount on the label.

The study, published Tuesday in JAMA, found that 22 of 25 melatonin gummy products analyzed—88 percent—were inaccurately labeled. That is, they contained over 10 percent more or less melatonin than what was listed on the packaging. Together, the dietary supplement products contained a range of melatonin that spanned 1.3 mg to 13.1 mg per serving. And those actual quantities represented a range of 74 percent to 347 percent of what they were supposed to contain based on their labeling.

The finding highlights a larger concern over the quality, safety, and effectiveness of dietary supplements, which are not vetted or approved by the Food and Drug Administration like over-the-counter medicines, such as ibuprofen and allergy medicines. The multi-billion dollar industry has long shrugged off substantial concerns over quality control, safety, lack of effectiveness data, and hyped health claims.

While the consequences of a melatonin overdose are unlikely to be acutely dangerous or life-threatening, the finding is concerning because melatonin can have unpleasant side effects, and it's commonly used for children. Gummy versions of the supplement, the focus of the current study, are particularly likely to be given to children.

Melatonin is a hormone produced by the brain in response to darkness, and supplement makers have sold it as a potential sleep aid and a relaxant. Although there are some studies indicating that melatonin supplements are better than a placebo at helping children sleep, the data is scant, and there is a lot of uncertainty about its use. Unknowns include the ideal dose and its timing, as well as long-term effects and whether it could alter hormonal development in children and young adults.

Rude awakening

Side effects and adverse events are also not well-documented. But in children, experts say melatonin risks include excessive drowsiness and increased bedwetting, plus many things that could disrupt sleep, such as headaches, nausea, nightmares, dizziness, and mood changes.

"Administration of as little as 0.1 mg to 0.3 mg of melatonin to young adults can increase plasma concentrations into the normal nighttime range," the authors of the JAMA study—led by Pieter Cohen, a supplement safety expert at Cambridge Health Alliance—wrote. Yet, the quantities in the gummies were 40 to 130 times higher than those amounts.

Cohen and colleagues note that an estimated 1.3 percent of US children took melatonin before the pandemic, and that number likely rose amid the stressful health emergency. Between 2012 and 2021, calls to poison control centers for children taking melatonin rose 530 percent, according to data published in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report. Those calls were associated with 27,795 emergency department and clinic visits, 4,097 hospitalizations, 287 intensive care unit admissions, and two deaths.

The new JAMA study has limitations; it only looked at gummy products and didn’t do batch-to-batch analysis. But, a study in 2017 by Canadian researchers looking at 31 melatonin supplements in chewable tablet, capsule, and liquid forms, found similarly wild variability in products. Melatonin content varied from 83 percent to 478 percent of what was written on labels, and batch-to-batch content varied as much as 465 percent. Moreover, 26 percent of the products also contained undisclosed amounts of serotonin, a neurotransmitter that can be harmful even in low amounts.

Last year, the American Academy of Sleep Medicine issued a health advisory over the use of melatonin, particularly in children. Parents are advised to talk with pediatricians before using the hormone, which the American Academy of Pediatrics also recommends.