A breaking study has linked long-term use of this popular supplement to a staggering heart risk increase. Still, you may not have to give it up for good.
Here’s insight you may already know by heart: getting enough sleep—ideally between seven and night hours per night—is crucial to your cardiovascular health. In fact, the American Heart Association says having a sleep disorder can increase your risk of several heart risk factors, including obesity, high blood pressure, diabetes, stress, and chronic inflammation. Those suffering from insomnia—an inability to fall asleep or stay asleep—may have a 45% higher risk of cardiovascular disease and a 54% higher risk of stroke within four years, their experts warn.
Given these statistics, it might seem that getting a good night’s sleep by any means necessary should improve heart health. However, a November 2025 study to be presented at this week’s American Heart Association’s Scientific Sessions 2025 in New Orleans suggests that a trusted “all-natural” sleep aid can come with costs if it’s used as a crutch too much.
Medical doctors compared five years of health records from nearly 131,000 middle-aged people diagnosed with chronic insomnia—65,000 of whom reported taking melatonin for more than a year—and found that adults taking melatonin to treat their insomnia for at least one year were 90% more likely to later develop heart failure, compared with those who had never taken melatonin.
That same cohort was also 3.5 times more likely to be hospitalized for heart failure and twice as likely to die during the study period, the researchers added.
“Melatonin supplements are widely thought of as a safe and ‘natural’ option to support better sleep, so it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors,” Ekenedilichukwu Nnadi, MD, an internal medicine physician and lead researcher of the study, said via press release, adding: “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
The Cleveland Clinic explains that heart failure, a condition currently affecting roughly 6.7 million American adults, occurs when the heart is unable to pump enough oxygen-rich blood to meet the body’s needs. “Your heart is still working. But because it can’t handle the amount of blood it should, blood builds up in other parts of your body. Most of the time, it collects in your lungs, legs and feet.”
If you hold your melatonin precious, it’s not all bad news: Though a 90% increase in risk may sound staggering, the absolute risk in both groups was still relatively low. Over the course of the five-year study, 4.6% of melatonin users developed heart failure, compared with 2.7% of non-users. Additionally, the researchers note that their work stopped short of proving causality—only an association between melatonin and heart failure.
However, given its widespread use—a 2022 Sleep Foundation survey states that 27% of U.S. adults and 4% of kids take melatonin—the study serves as an important reminder that the effects of long-term use are not fully understood. Marie-Pierre St-Onge, director of the Center of Excellence for Sleep & Circadian Research at Columbia University Irving Medical Center in New York, says: “People should be aware that [melatonin] should not be taken chronically without a proper indication.”
And, if you have a dependency on anything to help you sleep, it’s probably worth taking inventory of with your doctor.
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