Melatonin has become a go-to remedy for people struggling to fall asleep, especially in countries where it can be bought without a prescription.
But a new analysis presented at the American Heart Association’s annual scientific meeting has prompted researchers to look more closely at how prolonged use might affect long-term health.
The research team reviewed several years of electronic health records from more than 130,000 adults diagnosed with insomnia.
All individuals in the study had taken melatonin for at least a year, and anyone with pre-existing heart failure or on other sleep medications was excluded to avoid confounding factors.
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Patterns that concerned researchers
According to the team behind the study, people who had used melatonin continuously for a year or more appeared to face a higher chance of developing heart failure compared with individuals who had no recorded melatonin use.
Hospitalizations tied to heart failure and deaths from any cause also occurred more frequently in long-term users.
Ekenedilichukwu Nnadi of SUNY Downstate, who led the work, said in a press briefing that the findings should encourage clinicians to rethink how they guide patients who rely on over-the-counter sleep remedies.
However, he emphasized that the results show an association rather than clear evidence that melatonin directly causes harm.
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Several sleep specialists interviewed by Forskning.no offered a similar message of caution.
Sarah Bergen of Karolinska Institutet noted that insomnia itself is closely connected to cardiovascular risk, making it difficult to determine how much of the elevated risk is tied to the sleep disorder rather than the supplement.
More research is needed
Experts also pointed out that the study is currently available only as a conference abstract.
Without peer review or full publication, important details, such as the severity of participants’ sleep problems or whether they used non-prescription melatonin not captured in medical records, remain unclear.
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Bjørn Bjorvatn of the University of Bergen added that melatonin is generally considered a modest treatment for insomnia and is recommended mainly for circadian-rhythm disorders.
He argued that better-proven therapies might offer more benefit with fewer uncertainties.
While the findings are far from definitive, the early signals suggest that long-term melatonin use merits closer examination as researchers work to untangle the complex links between sleep, medications, and heart health.
Sources: Forskning.no, and American Heart Association.
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