Getting a good night's sleep isn't always easy, and for many people, melatonin has become part of their nightly routine. Often seen as a natural way to improve sleep, the supplement is widely used across the world.
But new research from the American Heart Association, reported by ScienceDaily, suggests its long-term use may deserve closer scrutiny.
Large study raises concerns
Researchers examined electronic health records from more than 130,000 adults diagnosed with chronic insomnia. They compared people who had documented melatonin use for at least one year with similar patients who had no recorded use of the supplement.
Over the following five years, long-term melatonin users were found to have around a 90% higher risk of developing heart failure than non-users. The study also reported higher rates of heart failure-related hospitalizations and a greater risk of death from any cause.
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The findings were presented at the American Heart Association's Scientific Sessions 2025. However, researchers stressed that the study identified an association rather than proving that melatonin directly caused the increased risks.
Important limitations
The research was based on data from the TriNetX Global Research Network, which contains anonymized medical records from healthcare systems around the world.
To reduce bias, participants were matched using dozens of health and demographic factors, while anyone with existing heart failure or prescriptions for other sleep medications was excluded.
Even so, the researchers acknowledged several limitations. In many countries, including the United States, melatonin is available over the counter, meaning some users may not have been recorded in medical records.
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The database also did not include information about the severity of participants' insomnia or certain mental health conditions that could have influenced the results.
More research needed
Because the study was observational, it cannot determine whether melatonin itself increases the risk of heart failure. Instead, it highlights a potential link that should be explored in future clinical research.
The researchers say further studies are needed before any changes to medical guidance can be recommended.
Until then, the findings serve as a reminder that even widely used supplements should continue to be evaluated for their long-term safety.
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This article is made and published by Mie Hermansen, who may have used AI in the preparation.