Long-Term Melatonin Use Linked to 90% Higher Heart Failure Risk in New Study

A large observational study presented at the American Heart Association's scientific conference suggests a significant link between prolonged melatonin use and an increased risk of heart failure. The research, which analyzed electronic health records of over 130,000 adults diagnosed with insomnia, found that individuals using melatonin for a year or more had approximately a 90% higher risk of developing heart failure in the subsequent five years compared to those who did not use the supplement. The study also reported higher rates of hospitalization for heart failure and increased all-cause mortality in the melatonin group.

Researchers meticulously matched participants based on 40 variables, including age, sex, medical history, and other medications, to minimize confounding factors. Despite these controls, the study's authors emphasize that it is observational and cannot prove causation. They acknowledge limitations, including the difficulty in definitively identifying who actually took the supplement, especially given its over-the-counter availability in many countries, and the potential for underlying severe insomnia or other health conditions to influence both melatonin use and heart health.

One of the study's lead authors, Dr. Ekenechukwu Nadi, stated that while the findings are surprising given melatonin's common perception as harmless, they warrant attention and may influence how doctors advise patients on sleep aids. However, he stressed that the study does not prove a cause-and-effect relationship and that underlying conditions like severe insomnia, depression, or anxiety could be contributing factors.

Experts not involved in the study highlighted that in the U.S., melatonin is not approved for treating insomnia and is sold as a supplement, raising concerns about inconsistent dosages and purity. In Israel, melatonin is regulated as a prescription drug, with specific formulations approved for older adults with insomnia, a policy that differs from much of the Western world. The article advises individuals using melatonin, particularly those in Israel who obtain it via prescription, to discuss its continued necessity and potential alternatives with their doctors, especially if they have a history of heart conditions. It cautions against abruptly stopping sleep aids and emphasizes that the study is not a basis for self-discontinuation.