Long-Term Melatonin Use Linked to Higher Heart Failure Risk in Chronic Insomnia Patients
- 4 days ago
- 2 min read
The perception of melatonin as a harmless, natural sleep aid has been challenged by a preliminary study linking its long-term use to significantly increased chances of a heart failure diagnosis, hospitalization, and death. The findings, which were presented at the American Heart Association’s Scientific Sessions 2025, raise serious concerns about chronic use, particularly among adults suffering from Chronic Insomnia.
Melatonin is a hormone naturally produced by the pineal gland to regulate the sleep-wake cycle. Synthetic, chemically identical versions are widely available over the counter in countries like the U.S., where supplements are not strictly regulated, meaning potency and purity can vary widely. Despite being promoted as a safe sleep aid, data on its long-term cardiovascular safety has been lacking.
Researchers, utilizing the TriNetX Global Research Network, reviewed five years of electronic health records for over 130,000 adults diagnosed with insomnia. The study classified those with documented use of melatonin for a year or more as the "melatonin group," comparing them to matched non-users who had never had the supplement recorded in their records. Crucially, all participants with a prior diagnosis of heart failure or who had been prescribed other sleep medications were excluded.
The results were described as "striking". Adults with insomnia who engaged in long-term Melatonin use (12 months or more) had approximately a 90% higher chance of incident heart failure over the five-year period compared with non-users (4.6% vs. 2.7%, respectively). Furthermore, participants taking melatonin were nearly 3.5 times as likely to be hospitalized for heart failure (19.0% vs. 6.6%) and nearly twice as likely to die from any cause over the five-year period (7.8% vs. 4.3%).
Lead author Dr. Ekenedilichukwu Nnadi pointed out that the consistent and significant increases in serious health outcomes were evident even after balancing for various other risk factors. However, both Dr. Nnadi and external experts cautioned against assuming direct causality. The study establishes an association, not a direct cause-and-effect relationship, suggesting that the underlying reason a person requires chronic melatonin use—such as severe insomnia, depression, or anxiety—might itself be the indicator of higher Heart Failure Risk.
Marie-Pierre St-Onge, Ph.D., an American Heart Association expert not involved in the study, expressed surprise that melatonin would be used chronically for insomnia, noting that in the U.S., it is not indicated for this chronic treatment. Because melatonin is often purchased over the counter, many users in the U.S. would not have documentation in their medical records, meaning the actual scope of chronic use may be underrepresented in the analysis.
The findings emphasize that the widely used supplement may not be as innocuous as commonly assumed. Experts agree that this observation warrants more extensive research, including randomized trials, to fully assess melatonin's long-term safety for the heart. Until then, individuals using melatonin for a year or more should consult with their physician to discuss their chronic use and underlying sleep issues.
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