AMERICA (Enmaeya News) - November 5, 2025
A new U.S. study has found that people who take melatonin regularly for sleep may face a significantly higher risk of developing heart failure, raising new questions about the safety of long-term supplement use.
Researchers reviewed medical records from more than 130,000 adults diagnosed with chronic insomnia and discovered that those who had been using melatonin for at least one year were about 90 percent more likely to develop heart failure within five years compared to non-users.
The same group also showed higher rates of hospitalizations and deaths related to heart failure.
Dr. Ekenedilichukwu Nnadi, a researcher at SUNY Downstate Medical Center and lead author of the study, cautioned that the findings do not prove melatonin directly causes heart disease.
“Melatonin supplements may not be as harmless as many assume,” he said, emphasizing that the data show an association, not causation.
The study, presented this week at the American Heart Association’s 2025 Scientific Sessions, is among the first large-scale analyses to explore a potential link between long-term melatonin use and cardiovascular outcomes.
Melatonin, a hormone that regulates the body’s sleep-wake cycle, is often marketed as a natural remedy for insomnia or jet lag. In many countries, including the U.S., it’s available over the counter leading many to believe it is entirely safe.
However, experts say that chronic melatonin use may indicate deeper issues, such as poor sleep hygiene or underlying health problems.
“People who take melatonin long-term tend to have more severe insomnia and may also have other risk factors, like anxiety or depression, which can themselves contribute to heart disease,” explained sleep medicine specialist Dr. Muhammad Rishi of the American Academy of Sleep Medicine.
“Melatonin isn’t necessarily dangerous,” said Dr. Rishi. “But its long-term effects are not well understood, and anyone relying on it nightly for months or years should talk to their doctor.”
The findings also highlight the need for patients and clinicians to look deeper into why someone is struggling to sleep. Non-pharmaceutical approaches like Cognitive Behavioral Therapy for Insomnia (CBT-I) are still the gold standard treatment, offering better long-term results without the potential side effects of supplements.
While melatonin is widely perceived as a “natural” and harmless sleep aid, this new research serves as a reminder that even over-the-counter products can carry risks when used long-term.
The study’s results are preliminary and have not yet undergone peer review. Still, the findings are prompting health experts to call for closer monitoring of supplement use among people with insomnia and cardiovascular risk factors.
