For countless individuals, melatonin has evolved into a nightly habit, a tiny tablet that offers the prospect of sleep in a hyperstimulated environment. However, fresh research unveiled at the American Heart Association’s Scientific Sessions 2025 indicates that prolonged usage of this well-known supplement may carry significant cardiovascular dangers.
In reviewing five years of health data from over 130,000 adults suffering from chronic insomnia, investigators discovered that those who utilized melatonin for a year or more faced a considerably increased likelihood of developing heart failure, being hospitalized due to the condition, or succumbing to any cause compared to those who didn’t use it. The revelations were disclosed on Monday, November 3, prior to the yearly AHA conference taking place in New Orleans.
Melatonin is a hormone produced naturally by the pineal gland to help control the body’s sleep-wake cycle. Available in synthetic form over-the-counter in the United States, it is widely regarded as a benign, natural sleep aide. Yet the study’s researchers assert that this viewpoint may not align with the evidence.
“Melatonin supplements could pose risks not typically recognized. If our findings are validated, this might influence how physicians advise patients regarding sleep aids,” remarked Ekenedilichukwu Nnadi, M.D., chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York.
Risks Elevate With Extended Use
The researchers utilized the TriNetX Global Research Network, a vast international database of anonymized patient records, to identify adults with confirmed insomnia who had used melatonin for over a year. These participants were compared with a control group of insomnia patients lacking any melatonin usage records. None had been diagnosed with heart failure beforehand or prescribed other sleep medications like benzodiazepines.
Over a five-year follow-up, the disparities were notable. Approximately 4.6 percent of long-term melatonin users experienced new heart failure, contrasted with 2.7 percent of non-users, signifying about a 90 percent higher risk. Individuals who had filled at least two melatonin prescriptions 90 days apart—an indication of regular use—were at an 82 percent escalated risk.
Rates of hospitalization and death conveyed a similar narrative. Melatonin users were 3.5 times more likely to be hospitalized for heart failure and nearly twice as prone to die from any cause during the study timeframe.
These results held steady after factoring in 40 matching variables, including age, gender, body mass index, and other cardiovascular issues. Nevertheless, the authors stressed that the study could not definitively establish that melatonin was the direct cause of heart complications.
“Worsening insomnia, depression or anxiety, or the concurrent use of other sleep-enhancing medications might correlate with both melatonin use and heart risk,” Nnadi mentioned. “Moreover, while the connection we uncovered raises safety concerns about this widely utilized supplement, our investigation cannot confirm a direct cause-and-effect link.”
Experts Advocate for Caution
Melatonin is not endorsed by the U.S. Food and Drug Administration for chronic insomnia treatment, yet its usage has surged in recent years. Between 1999 and 2018, self-reported melatonin consumption among U.S. adults increased fivefold, as per earlier studies. Some market formulations have significantly inconsistent doses, leading to uncertainty for users regarding their intake.
Marie-Pierre St-Onge, Ph.D., chair of the American Heart Association’s 2025 scientific statement on sleep health and a professor of nutritional medicine at Columbia University, remarked that the findings reveal a potential shortcoming in clinical guidance. “I’m astonished that medical professionals would prescribe melatonin for insomnia and allow patients to use it for more than a year, since melatonin, in the U.S., is not approved for insomnia treatment,” St-Onge noted. She was not part of the study.
The authors acknowledge several limitations. Since melatonin is sold over-the-counter in the U.S. but requires a prescription in the U.K., some users may have been inaccurately categorized in the data. The database also lacked details on insomnia severity, psychiatric coexisting conditions, and over-the-counter supplement usage. Still, the link between melatonin and negative cardiac outcomes remained strong across analyses.
As millions resort to supplements to handle sleep issues, the study emphasizes the necessity for more thorough investigations into their long-term safety. For the time being, specialists recommend first utilizing non-pharmaceutical strategies, such as adhering to regular sleep patterns, minimizing light exposure before sleep, and tackling stress or anxiety that could contribute to insomnia.
Additional studies will be necessary to substantiate these outcomes once the research is published in a peer-reviewed journal. However, for those viewing melatonin as devoid of risk, the data serve as a stark reminder: occasionally, the remedy for restless nights might carry an unforeseen price.
American Heart Association Scientific Sessions 2025: Abstract MP2306
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