Long-term use of melatonin supplements to support sleep may …

The association between melatonin and increased risk of heart failure or death found in this study, which cannot prove a cause-and-effect relationship, raises safety concerns about the use of melatonin, which is widely available, and may warrant more research on melatonin to assess its cardiovascular safety, researchers said.

https://newsroom.heart.org/news/long-term-use-of-melatonin-supplements-to-support-sleep-may-have-negative-health-effects