Studies suggest that long-term melatonin use may affect heart health
The American Heart Association reported Monday that long-term use of melatonin supplements may be linked to an increased risk of hospitalization for heart failure.
Melatonin is commonly used to treat insomnia and improve sleep, often marketed as a safe, natural alternative. However, data on its long-term cardiovascular protection are limited, prompting researchers to investigate its effects on heart health, particularly in adults with chronic insomnia.
The study analyzed five years of health records of 130,000 adults with insomnia. About 65,000 documented long-term melatonin use (defined as one year or more), while the rest had no melatonin recorded in their records. Patients with prior heart failure or other hypnotics were excluded.
The results showed that over five years, nearly 90 percent of adults with insomnia, whose records indicated long-term melatonin use, were more likely to develop heart failure, compared with nonusers. The researchers accounted for multiple risk factors and health conditions but still observed a significant association between long-term melatonin use and serious cardiovascular outcomes.
“Melatonin is generally seen as a very safe supplement… so we really didn’t expect to see a clear signal associated with higher rates of heart failure, hospitalization and death with long-term use,” lead researcher Ekendilichukwu Nadi said.
The study has not yet been peer-reviewed and experts urge the public to avoid caution.
“Although the association we found raises safety concerns about this widely used supplement, our study cannot prove a direct cause-and-effect relationship,” said Nadi. “This means more research is needed to test melatonin’s safety for the heart.”
The study has several limitations. They include the fact that over-the-counter melatonin use may not be captured in medical records, meaning some nonusers are actually taking the supplement. Other limitations include lack of data on insomnia severity and mental status.
Heart failure occurs when the heart cannot pump enough blood to meet the body’s needs and affects 6.7 million adults in the United States, according to the 2025 Heart Disease and Stroke Statistics.
