Recent findings suggest that prolonged use of melatonin supplements for sleep difficulties may carry unforeseen cardiovascular dangers. Chronic users have shown nearly double the risk of death and 3.5 times the likelihood of hospitalization due to heart failure.
A preliminary study presented at the American Heart Association's Scientific Sessions 2025 revealed that adults with long-term insomnia who took melatonin for over a year had a higher chance of developing heart failure, requiring hospitalization for heart-related issues, and experiencing mortality from all causes compared to non-users.
The findings will be discussed at the AHA's annual meeting, held November 7-10 in New Orleans, a major event for cardiovascular research updates.
Melatonin is a hormone produced by the pineal gland that helps regulate the sleep-wake cycle by increasing in darkness and decreasing with light exposure. Synthetic melatonin, identical to the natural hormone, is commonly used to treat insomnia and jet lag.
In countries like the U.S., melatonin supplements are sold over the counter without regulation, resulting in significant variability in product purity and dosage.
Although traditionally considered safe, experts now recommend exercising caution with long-term melatonin supplementation due to potential heart health risks.
Summary: Prolonged melatonin use may significantly increase risks of heart failure and death, prompting a need for cautious use and further research.