Approximately five million adults and four million children in the U.S. take melatonin to help their sleep. Experts worry that the supplement has serious potential risks, including heart failure.
Melatonin is made by the body and released as it gets dark outside. It cues the body to get tired. Supplementing melatonin can turn up how sleepy you are. People use it for insomnia, to speed up how quickly they fall asleep and ease jet lag.
A study from 2025 found a possible link between long-term use of melatonin and heart failure. It was published in the American Heart Association’s journal Circulation. The research looked at the medical records of 130,000 adults with insomnia. People who regularly used melatonin had a significantly higher risk of heart failure than those who didn’t.
The study concluded that using melatonin was “associated with an 89 percent higher hazard of incident heart failure, a three-fold increase in heart failure-related hospitalizations and a doubling of all-cause mortality.”
Even when there aren’t severe side effects, melatonin can have side effects. Even people who only occasionally take melatonin can experience daytime drowsiness, dizziness, headache and nausea.
Melatonin is the fourth most popular natural product taken by adults for health and the second most popular natural product for children. While this study doesn’t show that melatonin is necessarily unsafe, it does show that it needs to be studied more. It’s currently not recommended for children under the age of two.
"Melatonin supplements may not be as harmless as commonly assumed," medical scientist Ekenedilichukwu Nnadi at SUNY Downstate.
"Melatonin supplements are widely thought of as a safe and 'natural' option to support better sleep," said Dr. Nnadi. "So it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors."
We always say that no supplement is right for everyone. If a supplement is helpful, it’s because it’s doing something in your body. And if it’s doing something, for some people the results will be negative. That’s why it is essential to discuss your supplements with a doctor who knows your history and medications.
Some doctors say there is too little research to recommend giving melatonin to people under 18. And, if you or someone you love is struggling with sleep, the first thing to consider is sleep hygiene before turning to supplements. Having a bedtime routine, limiting screens, caffeine and blue light can all do wonders before you turn to melatonin.
