Key Highlights
- A study presented at the American Heart Association’s Scientific Sessions 2025 found that long-term use of melatonin supplements for insomnia is associated with a higher risk of heart failure and death.
- The research, involving more than 130,000 adults, suggests that melatonin may not be as harmless as commonly assumed, raising safety concerns among researchers and healthcare providers.
- Participants taking melatonin were nearly three times as likely to be hospitalized for heart failure and twice as likely to die from any cause compared to those not taking the supplement.
Risk of Heart Failure Linked to Long-term Melatonin Use
A preliminary study presented at the American Heart Association’s Scientific Sessions 2025 highlights potential adverse effects associated with long-term use of melatonin supplements. The research, which analyzed data from over 130,828 adults diagnosed with insomnia, found a concerning link between chronic melatonin consumption and increased risks of heart failure diagnosis, hospitalization for the condition, and overall mortality.
Study Design and Findings
The study utilized a large international database known as TriNetX to review electronic health records spanning five years. Participants were categorized based on their documented long-term melatonin use, defined as one year or more of continuous intake. Those who had never been prescribed melatonin formed the control group.
- Heart Failure Diagnosis: Adults with insomnia who used melatonin for at least a year had about a 90% higher risk of incident heart failure compared to non-users (4.6% vs. 2.7%).
- Hospitalization: Participants taking melatonin were nearly three and a half times as likely to be hospitalized for heart failure (19.0%) compared to those not using the supplement (6.6%).
- Mortality: The study also revealed that participants in the melatonin group were almost twice as likely to die from any cause over the five-year period (7.8% vs. 4.3%).
Researcher’s Perspective and Implications
Ekenedilichukwu Nnadi, M.D., lead author of the study and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care, emphasized that melatonin supplements may not be as harmless as commonly believed. “Melatonin is widely thought of as a safe option to support better sleep,” stated Dr. Nnadi, “but our findings suggest it could have serious long-term health implications.”
Dr. 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 multidimensional sleep health, echoed these concerns. She noted that melatonin supplements are commonly prescribed and taken chronically without a proper indication in the U.S., which is concerning given the potential cardiovascular risks identified by the study.
Limitations and Call for Further Research
The researchers acknowledged several limitations of their study, including variations in prescription availability across countries and potential confounding factors such as worse insomnia or other psychiatric disorders. They stressed that while their findings raise significant safety concerns, they cannot establish a direct cause-and-effect relationship between melatonin use and heart failure risk.
Dr. Nnadi concluded by highlighting the need for more research to test the cardiovascular safety of melatonin: “Our study highlights important safety concerns about this widely used supplement, but further investigation is needed to confirm our findings.”
The implications of these findings extend beyond individual patient care and could affect clinical guidelines and public health recommendations regarding the use of melatonin as a sleep aid. As such, healthcare professionals are advised to be cautious when recommending long-term use of this supplement.
