American Heart Association research links long-term use of melatonin supplements to higher heart risks
A Common Sleep Aid Under Scrutiny
Melatonin, a popular over-the-counter supplement used by millions to help fall asleep, might not be as harmless as once thought. A new study presented by the American Heart Association (AHA) at its Scientific Sessions 2025 in New Orleans has found that long-term use of melatonin could significantly increase the risk of heart failure and even death among adults with insomnia.
The Study and Its Findings
Researchers analysed health records from over 130,000 adults using data from the TriNetX Global Research Network, which tracks medical information across multiple countries.
Their findings were alarming:
People who used melatonin for more than a year were 90% more likely to develop heart failure.
These users were nearly twice as likely to die from any cause within five years.
They were also 3.5 times more likely to be hospitalised for heart failure.
The results suggest that melatonin use for sleep problems may not be as risk-free as commonly assumed.
“Melatonin supplements may not be as harmless as commonly assumed,” said Dr. Ekenedilichukwu Nnadi, the study’s lead author. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
What Is Melatonin and Why People Use It
Melatonin is a natural hormone produced by the brain that helps regulate sleep-wake cycles. It is often taken as a supplement to treat insomnia, jet lag, or sleep disorders.
In the United States, melatonin is widely sold over the counter and marketed as a “natural” solution for better sleep. However, because it is classed as a dietary supplement, it is not regulated by the U.S. Food and Drug Administration (FDA).
This means that potency and purity can vary significantly between brands — a factor that could influence its health effects.
Important Caveats: Correlation, Not Causation
Experts caution that the new study does not prove melatonin directly causes heart failure or death. The research relied on prescription and health record data, which means it might not include people who purchased melatonin without a prescription.
This limitation could mean that some melatonin users were misclassified as non-users, affecting the accuracy of comparisons.
“People should be aware that it should not be taken chronically without a proper indication,” said Marie-Pierre St-Onge, Chair of the AHA’s Writing Group on Sleep Health and Professor at Columbia University.
The Broader Health Context
Heart failure currently affects nearly 7 million Americans, a serious condition where the heart cannot pump enough blood to meet the body’s needs.
Chronic insomnia, meanwhile, is itself a risk factor for heart problems, often linked to stress, obesity, and high blood pressure.
The findings raise a key question: is melatonin contributing to the problem, or is its use a marker for people who already have poor cardiovascular health or severe insomnia?
Researchers say more studies are needed to confirm whether melatonin itself plays a role in developing heart issues or simply signals underlying problems.
Experts Urge Caution and Balance
Doctors emphasise that the results should not cause panic or lead everyone to stop taking melatonin immediately.
“The takeaway isn’t that melatonin is bad or that everyone should stop taking it,” Dr. Nnadi explained. “It’s that we shouldn’t assume something is risk-free just because it’s natural or sold over the counter.”
Experts recommend consulting a healthcare professional before using sleep aids regularly and exploring non-drug approaches such as:
Improving sleep hygiene (consistent bedtime, dark room, limited screen use)
Managing stress through relaxation or mindfulness
Addressing underlying sleep disorders with medical help
Key Takeaways
Long-term melatonin use (over one year) may raise the risk of heart failure by up to 90%, according to the AHA.
The study does not confirm that melatonin causes heart failure but suggests an important link worth further investigation.
Over-the-counter melatonin supplements vary in quality and dosage due to lack of FDA regulation.
Experts urge caution, especially for those using melatonin regularly without medical supervision.
Conclusion: A Reminder About “Natural” Supplements
This study serves as a reminder that even natural remedies can have unexpected risks. As researchers continue to explore the link between sleep aids and heart health, consumers are urged to use supplements wisely and seek professional advice before long-term use.
Melatonin may still help occasional poor sleepers, but experts agree that a balanced lifestyle and proper sleep habits remain the safest path to better rest and long-term health.
Sources:
American Heart Association Scientific Sessions 2025
TriNetX Global Research Network
Statements by Dr. Ekenedilichukwu Nnadi and Marie-Pierre St-Onge
U.S. Food and Drug Administration (FDA) guidance on dietary supplements
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