A new study has raised concerns about the long term safety of melatonin, a widely used sleep aid, after finding that adults with chronic insomnia who took the supplement for at least a year had a significantly higher risk of developing heart failure over the next five years.
Researchers analyzed electronic health records from the TriNetX Global Research Network, which includes de-identified patient data from multiple countries. They identified 130,828 adults diagnosed with insomnia, half of whom had been prescribed melatonin for at least 12 months. The remaining participants had no recorded melatonin use. Individuals with a prior diagnosis of heart failure or those prescribed other sleep medications like benzodiazepines were excluded from the study.
After adjusting for factors such as age, sex, race, existing health conditions, and medications, the researchers found that 4.6% of those who took melatonin developed heart failure within five years, compared with 2.7% of those who did not. The risk of hospitalization for heart failure was nearly 3.5 times higher in the melatonin group, with 19.0% hospitalized versus 6.6% in the comparison group. Death from any cause was also more common among melatonin users, with 7.8% dying during the five-year period compared with 4.3% in the non-melatonin group.
Ekenedilichukwu Nnadi, M.D., lead author of the study and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York, emphasized that the findings challenge the assumption that melatonin is a harmless sleep aid. “Melatonin supplements may not be as harmless as commonly assumed,” Nnadi said. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
Marie Pierre St Onge, Ph.D., C.C.S.H., FAHA, chair of the writing group for the American Heart Association’s 2025 scientific statement on sleep health, noted that melatonin is not indicated for long term use in the U.S., where it is available over the counter. “I’m surprised that physicians would prescribe melatonin for insomnia and have patients use it for more than 365 days,” she said. “People should be aware that it should not be taken chronically without a proper indication.”
The study authors stressed that their research was observational and cannot prove that melatonin directly caused the increased risks. They also highlighted several limitations, including the lack of data on where participants lived, the severity of their insomnia, or whether they had other psychiatric conditions. Melatonin use was only identified when it appeared in medical records, meaning some over-the-counter users may have been misclassified as nonusers. The researchers called for further studies to determine whether long-term melatonin use affects cardiovascular health and, if so, what mechanisms may explain the association
DISCUSSION (0)
POST A COMMENT