Study Links Long-term Melatonin Use to Heart Health Risks

Research indicates that long-term use of melatonin supplements may be correlated with an increased risk of heart failure. A study analyzing electronic medical records found that adults suffering from chronic insomnia who used melatonin for one year or more had a 90% higher chance of developing heart failure within the next five years compared to those who did not take the supplement. The findings raise significant concerns, particularly as melatonin is commonly viewed as a safe remedy for sleep issues.

In this comprehensive review, researchers examined the health records of over 130,000 adults within the TriNetX Global Research Network, a large international database. The average age of participants was around 55 years, with approximately 61.4% being women. The results showed that melatonin users were more than three times as likely to be hospitalized for heart failure and roughly twice as likely to die from any cause.

Despite these alarming findings, experts urge caution before drawing definitive conclusions about melatonin’s safety. The study has important limitations and has not yet undergone peer review. It will be presented at the American Heart Association’s Scientific Sessions 2025, scheduled for November 7-10.

Dr. Ekenedilichukwu Nnadi, the lead author and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care, remarked, “While the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship.” He emphasized the necessity for further research to evaluate melatonin’s safety concerning heart health.

Melatonin is a hormone produced naturally by the pineal gland in response to darkness, aiding the body’s transition into sleep. In supplement form, melatonin can be derived from animal sources or synthesized chemically. In the United States, melatonin is classified as a dietary supplement, exempting it from the rigorous scrutiny of the U.S. Food and Drug Administration. Consequently, products may contain more of the active ingredient than stated, or include harmful additives.

Chronic insomnia, impacting approximately 10% of the global population, is characterized by difficulty falling asleep or staying asleep for over three months. This condition can lead to adverse effects on memory, energy levels, mood, and overall quality of life. Health professionals can assist individuals in identifying whether insomnia stems from a standalone issue or an underlying medical condition, paving the way for tailored treatment strategies.

Melatonin use and its implications for heart health remain contentious. The research team classified participants based on documented melatonin use in their health records. Yet, the study faced criticism for its methodology. For instance, it included patients from countries like the United Kingdom, where melatonin requires a prescription, alongside those from the United States where it can be obtained over the counter. This could skew the control group’s reliability, as some may be taking melatonin without it being recorded.

Dr. Carlos Egea, president of the Spanish Federation of Sleep Medicine Societies, noted the importance of considering other influencing factors, such as the severity of insomnia and potential mental health issues, which were not accounted for in the study. Evidence suggests that insomnia is linked to a higher risk of cardiovascular events, including heart attacks and strokes.

While the study challenges previous findings, it is crucial to recognize that there are decades of consumer experience and research indicating that low-dose, short-term melatonin supplementation is safe for healthy adults. The Council for Responsible Nutrition pointed out that many clinical studies have shown positive outcomes for short-term use.

Before turning to melatonin or other sleep aids, experts advise individuals to consult with their healthcare providers. Dr. Marie-Pierre St-Onge, director of the Center of Excellence for Sleep & Circadian Research at Columbia University Irving Medical Center, stated, “People should be aware that melatonin should not be taken chronically without a proper indication.”

Healthy sleep hygiene practices—such as limiting light exposure and screen time before bed, maintaining a dark and quiet bedroom, and managing food and alcohol intake—are recommended as initial approaches to improve sleep quality. If supplementation is necessary, experts suggest looking for pharmaceutical-grade melatonin that has been independently tested for quality assurance.

As this evolving field of research continues, the implications for melatonin use and heart health will require ongoing scrutiny and further investigation to ensure safe practices for those seeking relief from sleep disturbances.