Key Highlights
- A preliminary study presented at the American Heart Association’s Scientific Sessions 2025 found that long-term use of melatonin supplements in adults with chronic insomnia was associated with a higher risk of heart failure diagnosis, hospitalization for heart failure, and death from any cause.
- The research analyzed data from over 130,000 adults with insomnia who had used melatonin for at least a year, finding they were more likely to be diagnosed with heart failure or die compared to non-users.
- While the study cannot prove a direct cause-and-effect relationship, it raises safety concerns about the long-term use of melatonin and suggests further research is needed to assess its cardiovascular safety.
- The findings highlight that melatonin supplements may not be as harmless as commonly assumed, especially when used for more than 365 days without proper indication.
Introduction to Melatonin Supplements and Insomnia
Melatonin is a hormone naturally produced in the body by the pineal gland, playing a crucial role in regulating sleep-wake cycles. It helps individuals fall asleep faster and stay asleep longer. Synthetic versions of melatonin are widely available over-the-counter in many countries, including the United States, where they are marketed as safe and natural options for treating insomnia.
Study Findings on Long-term Melatonin Use
A recent preliminary study presented at the American Heart Association’s Scientific Sessions 2025 examined the potential long-term effects of melatonin supplements in adults with chronic insomnia. The research, involving over 130,828 participants, found that those who used melatonin for more than a year were significantly more likely to experience heart failure or die from any cause compared to non-users.
Key findings included:
- About 90% higher risk of incident heart failure over five years (4.6% vs. 2.7%) among melatonin users.
- Nearly three and a half times the likelihood of being hospitalized for heart failure (19.0% vs. 6.6%).
- Nearly double the risk of death from any cause over five years (7.8% vs. 4.3%).
Expert Perspective and Implications
The lead author, Dr. Ekenedilichukwu Nnadi, emphasized that melatonin supplements may not be as harmless as commonly assumed, especially when used for more than a year without proper indication.
“Melatonin supplements are widely thought of as a safe and ‘natural’ option to support better sleep, so it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors,” Dr. Nnadi stated.
Dr. Marie-Pierre St-Onge, chair of the writing group for the American Heart Association’s 2025 scientific statement on multidimensional sleep health, added that physicians should be cautious about prescribing melatonin for insomnia and consider its potential long-term risks.
Future Research and Expert Recommendations
The study authors highlighted several limitations, including the use of a large international database with mixed prescription requirements for melatonin. They emphasized the need for further research to fully understand the cardiovascular safety of melatonin supplements.
“While the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship,” Dr. Nnadi noted. “This means more research is needed to test melatonin’s safety for the heart.”
Experts recommend that individuals with chronic insomnia consult healthcare providers before using long-term melatonin supplements and consider other sleep-enhancing strategies, such as cognitive behavioral therapy.
Conclusion
The findings of this preliminary study underscore the importance of thorough research into the safety of commonly used sleep aids like melatonin. As the use of over-the-counter supplements continues to grow, it is crucial for both healthcare providers and consumers to be aware of potential long-term health risks associated with their use.
