Long-Term Melatonin Use Linked to Significantly Increased Risk of Heart Failure, Death, New Study Finds
PARIS – A new study is raising serious concerns about the long-term safety of melatonin, a widely used and often perceived “natural” sleep aid. Researchers have found that adults taking melatonin for 12 months or more face a nearly 90% greater risk of developing heart failure over the next five years, alongside substantially increased risks of hospitalization and all-cause mortality. The findings,while preliminary and awaiting peer review,challenge the prevailing assumption of melatonin’s harmlessness and are prompting calls for caution regarding its chronic use.
For years, melatonin has been embraced as a safe and accessible solution for sleep disturbances, readily available as an over-the-counter supplement. Though, this new research suggests a potential dark side to prolonged use, revealing a statistically critically important link between long-term melatonin intake and severe cardiovascular consequences. The study’s results indicate that individuals consistently using melatonin experienced a 4.6% rate of heart failure advancement compared to 2.7% in non-users, a difference that researchers say warrants further investigation.
The study also revealed alarming increases in adverse outcomes among long-term melatonin users: a 3.5 times higher likelihood of hospitalization for heart failure (19.0% vs.6.6%) and nearly double the risk of death from all causes (7.8% versus 4.3%). These findings are particularly striking given melatonin’s widespread availability and the belief that it poses minimal health risks.
“People should know that melatonin should not be taken chronically without proper indication,” stated Dr. Ekenedilichukwu Nnadi, who led the study. He expressed surprise at the “consistent and significant increase in serious health problems,” even after accounting for other established risk factors.
Marie-Pierre saint-Onge, president of the drafting group for the 2025 scientific declaration of the American Heart Association on sleep and cardiometabolic health, echoed this sentiment, emphasizing that “people need to know that [melatonin] should not be taken chronically without appropriate indication.”
While the study has not yet undergone peer review, and researchers caution that it demonstrates a statistical association rather than definitive causation, the results are prompting a reevaluation of melatonin’s safety profile. Further research is planned to confirm these initial findings and determine the specific mechanisms by which long-term melatonin use may impact cardiovascular health.
