A preliminary study presented in 2025 drew attention by finding a higher occurrence of heart failure among adults with insomnia and long-term melatonin use documented in their medical records. An analysis published in 2026, involving a different population and a different way of measuring use, found no statistically significant association. Both studies are observational and do not allow the conclusion that melatonin causes — or prevents — heart disease.
Where the warning came from
In the analysis presented at an American Heart Association conference, researchers compared adults with chronic insomnia and records of melatonin use for at least 12 months with people with insomnia without such documentation. Over five years, heart failure was recorded in 4.6% of the group with documented use and 2.7% of the comparison group. The association was described as approximately 90% higher.
This result was released as a preliminary conference abstract, not as a randomized clinical trial. Electronic records do not perfectly capture who bought melatonin without a prescription, the dose, the actual duration of use, or the severity of insomnia. Anxiety, depression, other health problems, and greater contact with medical services may also influence both use and the likelihood of receiving a diagnosis.
What the 2026 analysis added
An article published in May 2026 in the journal Open Heart analyzed data from NHANES, a survey representative of the United States. In this study, use was defined as self-reported melatonin use in the previous 30 days, rather than as long-term treatment of people with insomnia. Among 50,929 adults with available data, 267 reported recent use. After adjustments, the analysis found no statistically significant association between recent use and cardiovascular disease or heart failure.
This is not a definitive answer regarding the safety of long-term use: the population, exposure period, and design are different. The authors describe the result as contextual and hypothesis-generating, not as proof of benefit or absence of risk.
What to do with the information
The headlines do not justify starting or stopping a product on your own. People who use melatonin for prolonged periods or continue to have persistent insomnia can talk with a professional about the indication, duration, dose, other medications, and possible causes of the problem. This news article does not provide individualized treatment guidance.
Sources
- Khan and Lima. Melatonin and cardiovascular risk: an NHANES reality check after recent heart failure concerns. Open Heart, 2026.
- American Heart Association: summary of the preliminary study presented in 2025 and acknowledged limitations.
Journalistic and educational content. This is not a recommendation to start or stop medications or supplements.