New research has raised concerns about the long-term use of melatonin supplements, which are widely available for purchase in the United States. With countless Americans having taken the supplement at least once in their lives, many are wondering if they are at risk of heart failure. So, could taking melatonin actually lead to heart failure?
Below, we break down the new study about melatonin and the risk, according to the data released by the American Heart Association as part of its Scientific Sessions.
Is Melatonin a Hormone?
Yes, melatonin is a hormone produced in the human body that helps the sleep cycle.
What Do Melatonin Supplements do?
Melatonin supplements help a person’s sleep-and-wake cycle. Those living with insomnia, for example, can take melatonin on a short-term basis to help their sleep pattern.
Taking melatonin at any point in the day can cause drowsiness.
Getting enough sleep feels good, and it’s good for you. Make it a habit, starting now! pic.twitter.com/8Sx1T48lqO
— American Heart Association (@American_Heart) October 29, 2025
Does Melatonin Cause Heart Failure?
Technically, yes, but it depends on how much melatonin you take. Researchers revealed in November 2025 that long-term supplement users were more than three times as likely to suffer from heart failure and twice as likely to die from any cause. Additionally, they found that more than 100,000 adults living with chronic insomnia and taking melatonin for more than one year had a 90 percent higher chance of experiencing heart failure over the next five years.
However, the American Heart Association’s news release pointed out that the discovery “cannot prove a cause-and-effect relationship” even though it raised safety concerns about the long-term usage of the supplement.
The preliminary research will be presented at the American Heart Association’s Scientific Sessions 2025 this month, the AHA revealed in a news release.
Is it Still Safe to Take Melatonin?
Yes, short-term usage of melatonin is still safe, but the new research still raises concerns for those who have taken melatonin over the counter for more than one year. Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, and chair of the writing group for the American Heart Association’s 2025 scientific statement, said she was “surprised that physicians would prescribe melatonin for insomnia and have patients use it for more than 365 days, since melatonin, at least in the U.S., is not indicated for the treatment of insomnia.”
“In the U.S., melatonin can be taken as an over-the-counter supplement, and people should be aware that it should not be taken chronically without a proper indication,” St-Onge said, per the AHA’s news release.
