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Long-term melatonin use linked to higher heart failure risk in observational study

A preliminary analysis of 130,828 adults with chronic insomnia found increased rates of heart failure, hospitalization, and death among long-term melatonin users.

Updated Aug 29, 2026 · 14:23 UTC1 reports

The short version

  • A preliminary study presented at the American Heart Association's Scientific Sessions 2025 linked documented melatonin use of one year or more to a 90% higher five-year risk of developing heart failure among adults with chronic insomnia.
  • Long-term melatonin users in the study experienced higher rates of heart failure hospitalizations (19.0% vs. 6.6%) and overall mortality (7.8% vs. 4.3%) compared to a matched control group.
  • Researchers emphasized the observational study demonstrates an association rather than a direct cause-and-effect relationship.
  • Further research is required to determine whether melatonin directly impacts cardiovascular health or if underlying factors like insomnia severity drive the observed risks.

Key facts

  • An analysis of 130,828 adults with chronic insomnia found that 4.6% of long-term melatonin users developed heart failure over five years compared to 2.7% of non-users.[ScienceDaily]
  • Participants with recorded long-term melatonin use were nearly 3.5 times as likely to be hospitalized for heart failure compared to the control group.[ScienceDaily]
  • All-cause mortality over the five-year observation period was 7.8% among melatonin users compared to 4.3% in the comparison group.[ScienceDaily]
  • In a sensitivity analysis requiring at least two filled melatonin prescriptions 90 days apart, the associated heart failure risk remained 82% higher.[ScienceDaily]
  • The study utilized de-identified health records from the TriNetX Global Research Network, evaluating patients with a mean age of 55.7 years, 61.4% of whom were women.[ScienceDaily]

What remains uncertain

  • The study's observational design cannot establish whether melatonin directly causes heart failure or cardiovascular complications.[ScienceDaily]
  • Over-the-counter melatonin consumption without medical record entry could not be tracked, creating potential misclassification between user and non-user groups.[ScienceDaily]
  • Researchers lacked data on insomnia severity and psychiatric comorbidities, which could independently influence both melatonin usage and cardiovascular health.[ScienceDaily]

Sources