Study Links Long-Term Melatonin Use to Significantly Higher Heart Failure Risk

A large preliminary study has raised questions about the long-term cardiovascular safety of melatonin, a widely used sleep supplement. Researchers found that people with chronic insomnia who had documented melatonin use for at least one year had higher rates of heart failure, heart failure hospitalization and death over the following five years.

Presented at the American Heart Association’s Scientific Sessions, the study analyzed health records of 130,828 adults with insomnia from the TriNetX research network. Researchers excluded people with existing heart failure and matched melatonin users with nonusers across 40 health and demographic factors.

Adults with insomnia and documented long-term melatonin use had about a 90% higher risk of developing heart failure compared with matched nonusers. Heart failure occurred in 4.6% of the melatonin group versus 2.7% of the comparison group.

In a separate analysis requiring at least two prescriptions filled 90 days apart, the increased risk remained at 82%.

Hospitalization for heart failure was also substantially more common among melatonin users, occurring in 19.0% compared with 6.6% of nonusers. Death from any cause was reported in 7.8% of melatonin users versus 4.3% of nonusers.

However, researchers emphasize that these findings do not prove melatonin caused the increased risks.

The study was observational, and several important factors were unavailable, including the severity of insomnia and certain psychiatric conditions. People with more severe insomnia, anxiety or depression may be more likely to use melatonin and may independently have greater cardiovascular risk.

Another limitation is that melatonin is available over the counter in countries such as the U.S. Researchers could identify use only when it appeared in medical records, potentially misclassifying some users as nonusers.

Therefore, researchers say more studies are needed before conclusions can be drawn about melatonin's long-term heart safety. The findings do, however, challenge the assumption that a “natural” sleep supplement is necessarily harmless when used chronically.

REFERENCE: American Heart Association. "Long-term melatonin use linked to 90% higher heart failure risk." https://newsroom.heart.org/news/long-term-use-of-melatonin-supplements-to-support-sleep-may-have-negative-health-effects?preview=8064&preview_mode=True