Melatonin Use Linked to Increased Heart failure Risk in Large-Scale Study
ORLANDO, FL – November 6, 2025 – A five-year study involving over 130,000 individuals with insomnia raises concerns about the long-term cardiovascular effects of melatonin supplementation. Researchers have found a 90% greater likelihood of heart failure among those who consistently used melatonin for at least 12 months, a finding that could reshape how physicians counsel patients struggling with sleep.
The research,set to be fully presented tomorrow at the American Heart Association 2025 Scientific Sessions,highlights a potential risk previously underestimated in the widespread use of the sleep aid. While the study participants all obtained melatonin via medical prescription, the availability of the hormone over-the-counter in countries like the United States and Portugal raises questions about the potential impact of self-medication on broader public health. Experts emphasize the importance of allowing the body’s natural sleep-wake cycle to function, as melatonin is a hormone naturally produced by the body, with levels rising in darkness and falling during daylight.
the study tracked individuals experiencing insomnia and their melatonin usage over a five-year period. The observed correlation between prolonged melatonin use and increased heart failure risk warrants further investigation, researchers say. It’s important to note that the study demonstrates an association, not necessarily causation, and the underlying health conditions of participants could contribute to the findings.
Currently,melatonin is classified as an over-the-counter food supplement in Portugal,readily available in pharmacies and supermarkets. Though, medical supervision is strongly advised, especially when considering melatonin use in children. In the United States,unlike Brazil,melatonin is also accessible without a prescription,possibly leading to widespread self-treatment.
experts caution against relying on supplemental melatonin,advocating rather for establishing healthy sleep routines that support the body’s natural production of the hormone.The complete findings and detailed analysis of the study will be unveiled at the American Heart Association’s conference on November 7th.
