Melatonin is often seen as a safe, natural sleep aid, but new research shows it may not be as harmless as many people think. A large international study found that adults who used melatonin for more than a year had a higher risk of heart failure, hospitalization, and even death compared to those who didn’t take it. The findings, presented at the American Heart Association’s 2025 Scientific Sessions, challenge the idea that melatonin is risk-free for long-term use.
Researchers looked at data from more than 130,000 adults with chronic insomnia. Those who used melatonin long-term were 90% more likely to develop heart failure within five years. They were also nearly 3.5 times more likely to be hospitalized for heart failure and almost twice as likely to die from any cause.
These risks stayed high even after accounting for age, blood pressure, and other health conditions. Experts warn that melatonin was never meant for daily, long-term use — especially since supplement quality can vary widely.
The study doesn’t prove that melatonin directly causes heart problems, but it raises concerns about overuse. Sleep experts recommend improving sleep naturally instead. Good habits like keeping a consistent bedtime, managing stress, and getting morning sunlight can help reset the body’s natural rhythm. Melatonin, they say, should be used only for short-term issues like jet lag — not as a nightly fix.
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