Preliminary Study Links Long-Term Melatonin Use to Higher Heart-Failure Rates — Experts Urge Caution, Not Panic

Preliminary study raises questions about long-term melatonin use — but experts say don’t panic

WASHINGTON — Headlines tying melatonin to heart failure have prompted concern, but cardiology experts caution that the new findings are preliminary and do not prove cause and effect.

What the study found

Researchers analyzing international electronic health records followed adults diagnosed with insomnia who had a melatonin prescription suggesting at least one year of use. Over five years, 4.6% of those chronic melatonin users were reported to develop heart failure, compared with 2.7% of insomnia patients whose records showed no melatonin prescription. The analysis was presented at an American Heart Association meeting but has not been peer reviewed.

Important limitations

Experts emphasize several key limits to interpreting the results:

• The study is observational, so it cannot prove melatonin caused the higher rate of heart failure; underlying insomnia or other health differences could explain the association.
• Only some countries require a prescription for melatonin. In the United States it is sold over the counter, so American use may not be captured in prescription records.
• The report did not include information on melatonin doses or product quality. Over-the-counter supplements are not regulated for consistent potency or purity, so ingredients and concentrations can vary by brand.
• Residual confounding is possible: patients prescribed melatonin long-term may differ in illness severity, other medications, or health behaviors that affect heart risk.

“We should not raise the alarm and tell patients to stop taking all their melatonin,” said Dr. Pratik Sandesara, an interventional cardiologist at Emory Healthcare who was not involved in the research. Dr. Clyde Yancy, chief of cardiology at Northwestern University, noted the study does not establish harm but also does not support indefinite use.

What clinicians recommend

Physicians typically advise using melatonin for short-term needs such as jet lag or temporary sleep disruption, and recommend discussing chronic use with a clinician. Improving sleep habits remains a cornerstone of treatment for insomnia and is supported by robust evidence.

Practical sleep tips

• Keep your bedroom dark and cool.
• Avoid bright and blue light from screens in the hour or two before bedtime.
• Maintain a regular sleep-wake schedule and a relaxing pre-sleep routine.
• Talk with your doctor if you have persistent sleep problems before starting or continuing long-term supplements.

Bottom line: The study raises a signal that merits further research, but it does not prove melatonin causes heart failure. Patients with concerns should consult their health care provider rather than stopping medication abruptly.

Correction: The Northwestern University cardiology chief is Dr. Clyde Yancy (not Yancey).

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.