If you’re having trouble sleeping, think twice before using melatonin.
New research suggests that long-term use of the popular sleep aid may be linked to increased risk of heart failure and even early death. Medical experts caution that the findings are preliminary and should not cause undue concern.
Data from the American Heart Association (AHA) shows adults who took melatonin for more than a year had a 90% higher risk of heart failure than non-users. The study will be presented at the AHA’s Scientific Sessions 2025 in New Orleans. Researchers analyzed five years of health records from more than 130,000 adults with insomnia and found troubling trends among chronic users.
“Melatonin supplements may not be as harmless as commonly assumed,” said Dr. Ekenedilichukwu Nnadi, the study’s lead author and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
The researchers found that regular users were almost twice as likely to develop heart failure. They were more than three times as likely to be hospitalized and nearly twice as likely to die during the study period compared to people who did not take the supplement. The findings reveal a strong association, but the authors emphasize that the data do not directly prove that melatonin causes heart problems.
“There’s no evidence that melatonin supplements themselves cause heart problems,” Nnadi clarified. Chronic use may instead signal deeper health issues like high blood pressure, insomnia, depression, or anxiety. All these conditions can increase the risk of heart failure.
The study has some limitations. Melatonin is available over the counter in the United States, so its use is not typically recorded in medical records. Some long-term users may have been incorrectly classified as non-users.
“The findings are certainly provocative and warrant attention,” said Dr. Muhammad Rishi, associate professor of clinical medicine and spokesperson for the American Academy of Sleep Medicine, in an interview with The Washington Post. “However, the study is observational and based on electronic health record data, which limits its ability to establish causality.”
Melatonin is a hormone made by the brain’s pineal gland. It helps control the sleep-wake cycle. Synthetic melatonin is sold as gummies, pills, and liquids, and is promoted as a safe, “natural” sleep aid. But supplements are not regulated by the Food and Drug Administration (FDA). This means the dose and purity of melatonin can vary between brands.
A 2022 Sleep Foundation survey found that 27% of U.S. adults and about 4% of children regularly take melatonin. The number has grown as more Americans struggle with sleep. The Centers for Disease Control and Prevention estimates that almost 7 million Americans have heart failure. This is a condition where the heart cannot pump enough oxygen-rich blood through the body.
Some experts argue that the problem is not melatonin itself, but rather why people use it. “Poor sleep can cause poor heart health,” said Dr. Joyce Oen-Hsiao, an associate professor at Yale School of Medicine. “Insomnia and chronic stress can raise blood pressure and inflammation. Both are major risk factors for heart failure.”
Nnadi said that more research is needed before firm conclusions can be drawn. “While the link we found raises safety concerns about the supplement, our study cannot prove a direct cause-and-effect relationship,” he said. “We need more studies to test if melatonin is safe for the heart.”
Experts say people should not take melatonin every night without medical advice. Marie-Pierre St-Onge, director at Columbia University’s Center of Excellence for Sleep & Circadian Research, said, “People should be aware it should not be taken chronically without a proper reason.”
Doctors suggest talking to a healthcare provider before using melatonin long-term. They also recommend behavioral treatments like cognitive behavioral therapy for insomnia (CBT-I), which can offer lasting benefits without the risks of supplements.
The AHA study suggests that persistent sleep problems could signal underlying heart health issues, reinforcing the importance of careful consideration before using melatonin long-term.
