Although melatonin is commonly considered safe for sleep improvement, new research suggests that prolonged use could lead to significant heart problems.
A preliminary study presented at the American Heart Association's Scientific Sessions 2025 revealed that adults with chronic insomnia who took melatonin for one year or more experienced nearly double the risk of death and were 3.5 times more likely to be hospitalized for heart failure compared to those who did not use the supplement.
The findings will be further discussed during the AHA's annual conference held from November 7 to 10 in New Orleans, which serves as a major platform for sharing advancements in cardiovascular science and clinical research.
Melatonin is a natural hormone produced by the pineal gland that controls the sleep-wake cycle, increasing during darkness and decreasing in daylight. Synthetic melatonin, chemically identical to the natural hormone, is commonly used to treat insomnia and jet lag.
Melatonin supplements are available over the counter in many countries, including the U.S. However, the lack of strict regulation in the U.S. means product purity and dosage can vary significantly.
"Adults with chronic insomnia who used melatonin for a year or longer were more likely to develop heart failure, be hospitalized for heart failure, and die from any cause than those who did not take the supplement."
Experts now recommend exercising caution with long-term melatonin use due to these potential cardiovascular risks.
Author's summary: New evidence links extended melatonin use to increased heart failure risk and mortality, urging careful consideration of long-term supplementation.