Nathan López Bezerra
About the study
Melatonin has long been a popular sleep aid for people with insomnia, often marketed as a safe and natural option. But new research presented at the American Heart Association’s 2025 Scientific Sessions suggests that long-term use of this hormone supplement may be linked to heart failure.
Researchers reviewed five years of health records for more than 130,000 adults who had been diagnosed with insomnia and had taken melatonin for at least one year. They compared their cardiovascular outcomes with those of people who did not take melatonin.
Melatonin use, insomnia & heart concerns
The study found that about 4.6% of long-term melatonin users developed heart failure, compared with 2.7% of non-users — a roughly 90% higher risk. Among melatonin users, 19% were hospitalized for heart failure, versus 6.6% of non-users. Over the five-year period, 7.8% of melatonin users died from any cause, compared with 4.3% of non-users.
“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,” said Ekenedilichukwu Nnadi, M.D., the study’s lead author, in a statement.
The researchers stressed that the findings show an association, not proof of cause and effect. Still, they said the consistency of the results is reason for caution.
What does this mean for melatonin use?
“Melatonin supplements may not be as harmless as commonly assumed. If our study is confirmed, this could affect how doctors counsel patients about sleep aids,” Nnadi said. But there are important nuances. Chronic insomnia itself is linked to a higher risk of heart problems, including heart failure. People who use melatonin for more than a year may have more severe sleep disruptions, and melatonin use could be a marker of poor sleep health rather than the direct cause of heart issues.
The study identified melatonin users through prescription records. In the United States, melatonin is sold over the counter, so many U.S. users may have been incorrectly counted as non-users. That misclassification could make the difference between groups appear larger or smaller. Experts have long warned about unknown safety effects of melatonin, and this study adds to the concern. Short-term use at appropriate doses may be acceptable for occasional jet lag, but nightly long-term use is not advised.
What else can you take and do for sleep?
For people with insomnia or general sleep trouble, alternatives exist. Improving sleep hygiene — such as avoiding alcohol before bed, keeping the room dark and cool, and reducing screen time — is a good starting point. For those seeking a supplement, magnesium is often recommended. Magnesium is an essential mineral that many people (about 43%) do not get enough of from diet alone. Low magnesium levels can contribute to stress, muscle tightness, restless sleep, and mood shifts.
Taking magnesium before bed may help ease the body and mind into relaxation. It activates receptors for GABA, a neurotransmitter that quiets an overactive nervous system and promotes calm, making it easier to fall asleep and stay asleep. The article also notes that a list of top sleep supplements was compiled, with the best overall option being a magnesium-based product.
The takeaway
While this study is preliminary, it suggests that long-term nightly use of melatonin may carry more risks than previously thought. Short-term use, good sleep habits, and supportive nutrients like magnesium remain safer ways to improve sleep naturally.
