Melatonin Use Linked to Increased Heart Failure Risk, Preliminary Study Finds New research presented by the American Heart Association suggests that long-term melatonin use may be linked to a higher risk of heart failure , though medical experts stress that more data is needed before drawing firm conclusions. Study Overview and Key Findings According to the preliminary study, adults with insomnia who took melatonin for at least one year had about a 90% greater chance of developing heart failure over five years compared to those who did not use the supplement . The findings will be presented at the American Heart Association’s Scientific Sessions 2025 in New Orleans. Dr. Ekenedilichukwu Nnadi, the study’s lead author and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care , said that the results suggest melatonin may not be as harmless as often assumed . He noted that if further research confirms these findings, it could change how doctors advise patients about using sleep aids. Data and Participant Details The research analyzed five years of health data from more than 130,000 adults diagnosed with insomnia . About half of them had been prescribed melatonin and used it for a year or longer. Those in the melatonin group faced higher risks not only of developing heart failure but also of hospitalization and death from any cause. In a secondary analysis, melatonin users were found to be 3.5 times more likely to be hospitalized for heart failure and nearly twice as likely to die from any cause compared with non-users. However, experts emphasize that the study is observational and cannot establish a direct cause-and-effect relationship. Broader Context on Melatonin Use Melatonin, produced naturally by the pineal gland , helps regulate the body’s sleep-wake cycle. Synthetic versions are commonly used to treat insomnia and jet lag. While the supplement is considered safe for short-term use, questions remain about its long-term cardiovascular safety. Dr. Marie-Pierre St-Onge of Columbia University , chair of the American Heart Association’s 2025 sleep health statement, said she was surprised that patients were prescribed melatonin for more than a year, as it is not officially indicated for chronic insomnia. The study authors acknowledged several limitations , including differences in prescription regulations between countries and the potential undercounting of over-the-counter use in the U.S. They emphasized that more research is needed to confirm whether melatonin directly increases heart failure risk. Until the findings are published in a peer-reviewed journal, the results remain preliminary. The American Heart Association cautioned that the conclusions reflect only the authors’ analyses and do not represent the organization’s official stance.
