Millions of people use melatonin as a readily available sleep aid, but emerging research suggests a potential link between long-term use and an increased risk of heart problems. A recent study presented at the American Heart Association’s Scientific Sessions 2025—though not yet peer-reviewed—found that consistent melatonin users exhibited higher rates of heart failure, hospitalizations, and mortality compared to those who did not take the supplement.
The Study’s Findings
Researchers followed over 130,000 adults—65,414 melatonin users and a control group of the same size—for five years. The results revealed significant differences between the groups:
- Heart Failure: 4.6% of melatonin users (3,021 people) developed heart failure, compared to 2.7% (1,797 people) in the control group—a roughly 90% higher risk.
- Hospitalizations: 19% of melatonin users (12,411 people) were hospitalized for heart failure, versus 6.6% (4,309) of non-users—making melatonin users 3.5 times more likely to require hospitalization.
- All-Cause Mortality: Melatonin users had nearly twice the mortality rate over the five-year period compared to those who did not take the supplement.
What This Means
These findings raise questions about the long-term safety of melatonin, particularly as it’s widely available over-the-counter and often perceived as harmless. However, it’s crucial to understand that correlation does not equal causation. The study does not prove that melatonin causes these heart issues, only that an association exists.
Why This Matters
The widespread use of melatonin, often as a self-treatment for sleep problems, underscores the need for better understanding of its potential effects. Many people assume over-the-counter supplements are inherently safe, but this study challenges that assumption.
Potential Explanations
Several factors could explain the observed link between melatonin use and heart problems. First, individuals with chronic insomnia often have underlying health conditions—such as anxiety, depression, obesity, hypertension, or diabetes—that independently increase their risk of heart failure. Second, melatonin supplements in the U.S. are largely unregulated, meaning doses may vary significantly from what’s listed on the label. High or inconsistent doses could disrupt the body’s natural circadian rhythm, potentially affecting blood pressure, heart rate, and vascular tone.
The Role of Underlying Health
It’s important to note that melatonin may actually benefit some individuals with heart failure, according to decades of prior research. However, the new study suggests that in certain populations—particularly those with pre-existing health conditions—long-term melatonin use may carry risks.
How to Use Melatonin Safely
If you’re considering melatonin, start with the lowest effective dose and avoid daily use. Consult a healthcare professional to discuss whether melatonin is appropriate for you, especially if you have underlying heart problems or other health conditions.
Conclusion
The study highlights the need for more research into the long-term effects of melatonin. While the supplement remains widely available, consumers should exercise caution and consult healthcare professionals before using it, particularly for extended periods. The findings serve as a reminder that even over-the-counter supplements can have unintended consequences, and informed decision-making is crucial for protecting cardiovascular health
