Long-Term Melatonin Use May Raise Heart Failure and Death Risk

New research suggests long-term melatonin use may increase the risk of heart failure, hospitalization and death in people with insomnia. While widely considered safe, experts urge caution and recommend medical guidance for extended melatonin use.

For years, melatonin has been seen as a harmless, “natural” sleep remedy. But new research presented at the American Heart Association’s 2025 Scientific Sessions suggests that long-term use may come with surprising dangers for heart health.

What the Study Found

Scientists reviewed medical data from over 130,000 adults with chronic insomnia. They compared people who took melatonin for at least a year with those who never used it. The results were striking: long-term melatonin users were significantly more likely to develop heart failure, be hospitalized for the condition, or die from any cause.

Researchers found that melatonin users had nearly double the risk of heart failure and were more than three times as likely to need hospitalization for the condition. They also showed a higher risk of death during the five-year follow-up.

Why Melatonin May Pose Risks

Melatonin is a natural hormone that regulates sleep, but in supplement form it often comes in much higher doses than the body produces. In many countries, especially the U.S., melatonin is sold over the counter without strict regulation, meaning dosage and purity can vary greatly.

Experts Urge Caution

Experts caution that this study does not prove melatonin causes heart problems — it only shows a strong link. Other factors, such as severe insomnia, anxiety, or use of additional sleep aids, may also contribute. Still, the findings suggest that long-term daily use should be approached with caution.

Health specialists recommend treating melatonin like a medication rather than a wellness supplement: use it only when needed, avoid long-term self-use, and speak with a doctor if sleep issues persist. Better sleep habits, therapy for insomnia, and medical guidance may be safer long-term options.