A recent study presented at the American Heart Association’s Scientific Sessions 2025 suggests that extended use of melatonin supplements may be associated with a significantly higher risk of heart failure.

Researchers analyzed medical records from nearly 131,000 adults diagnosed with insomnia, discovering that individuals who used melatonin for over 12 months had a 90% greater risk of developing heart failure within five years compared to non-users. Those who filled multiple prescriptions at least 90 days apart faced an 82% higher risk.

Long-term melatonin users were also found to be 3.5 times more likely to be hospitalized for heart failure and twice as likely to die during the study period.

Lead author Dr. Ekenedilichukwu Nnadi of SUNY Downstate noted that the results were “striking,” given melatonin’s reputation as a natural and safe sleep aid. However, experts emphasize that the findings show an association, not a direct cause-and-effect link.

Cardiologists caution that unregulated supplement dosages, underlying conditions like sleep apnea, and other sleep medication use could influence the outcomes. They recommend limiting long-term melatonin use and exploring non-medication-based solutions such as consistent sleep routines, reduced blue light exposure, and stress management.

While further research is required to confirm causality, the findings highlight the need for greater awareness and regulation surrounding long-term melatonin supplementation.

Source: American Heart Association Scientific Sessions 2025