A new study has found that adults who take melatonin for more than a year may face a higher risk of heart failure, hospitalization, and death. The findings were presented at the American Heart Association’s Scientific Sessions 2025.
Researchers tracked over 130,000 adults diagnosed with chronic insomnia. Among those who used melatonin for at least a year, 4.6 percent developed heart failure within five years, compared with 2.7 percent of non-users. Long-term melatonin users were also more than three times as likely to be hospitalized for heart failure and had nearly double the risk of dying from any cause during the study period.
Dr. Ekenedilichukwu Nnadi, who led the research, cautioned that the study does not prove melatonin directly causes heart failure. “People who take melatonin every night may simply have more severe insomnia, which itself could raise heart risks,” he said. He added that the large size and careful design of the study make the findings noteworthy.
Melatonin is a hormone naturally produced by the body and is widely sold as an over-the-counter sleep aid. Its use has more than doubled in the past decade, especially among adults with chronic insomnia.
The study focused on prescribed melatonin and found consistent results when tracking multiple prescriptions, suggesting that long-term use, rather than occasional use, is linked to higher heart risks. Over-the-counter use was not fully captured in medical records, so some non-users may have taken melatonin without reporting it.
Experts advise caution with long-term melatonin use. Dr. Muhammad Rishi, a sleep medicine physician, said melatonin should be treated like a drug, starting with the lowest effective dose for short-term use. Persistent insomnia should prompt evaluation by a medical professional to identify underlying conditions such as sleep apnea, restless legs syndrome, or chronic pain.
“Melatonin is not risk-free just because it is natural or sold over the counter,” said Dr. Nnadi. “Our study is a reminder that more isn’t always better, and we need stronger evidence before calling any supplement heart-healthy.”
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