New research suggests that melatonin — a popular over-the-counter sleep aid — may be linked to an increased risk of heart failure, though experts caution that more evidence is needed before drawing firm conclusions.
According to a press release from the American Heart Association (AHA), long-term melatonin use was associated with a higher likelihood of developing heart failure, as well as a greater risk of hospitalization or death due to the condition. The findings come from a preliminary study that will be presented at the AHA’s Scientific Sessions 2025, beginning Nov. 7.
The study analyzed five years of health records from over 130,000 adults diagnosed with insomnia who had taken melatonin for at least a year. Researchers found that these individuals had a 90% higher risk of heart failure over a five-year period compared to those who didn’t take melatonin.
However, experts stress that the study’s results do not prove that melatonin causes heart problems.
The study defined melatonin users as patients who were prescribed the supplement, but in the U.S., melatonin is available over the counter, meaning that some regular users may have been incorrectly classified as non-users — potentially skewing the data.
Melatonin is a hormone that helps regulate the body’s sleep cycle and is widely used by adults and children to combat insomnia. However, experts note that poor sleep itself can harm heart health.
Dr. Joyce Oen-Hsiao, an associate professor of cardiovascular medicine at the Yale School of Medicine, told The Washington Post that insomnia can be both a symptom and a risk factor for cardiovascular disease.
Dr. Nnadi also emphasized that several other factors — such as depression, anxiety, or the use of other sleep medications — could contribute to both melatonin use and increased heart risk.
