Overview
- Researchers reviewed five years of electronic health records for nearly 131,000 adults with chronic insomnia, comparing about 65,000 with at least 12 months of recorded melatonin use to matched non-recorded users.
- Recorded long-term users had about a 90% higher rate of incident heart failure, were nearly 3.5 times more likely to be hospitalized for heart failure, and had higher all-cause mortality over the follow-up period.
- The study was presented at the American Heart Association Scientific Sessions and has not been peer-reviewed, so it cannot determine that melatonin causes these outcomes.
- Methodological gaps include reliance on prescription/EHR records that can miss over-the-counter use, lack of data on dose, adherence and insomnia severity, and potential confounding by conditions like sleep apnea or early cardiac disease.
- Clinicians advise against abrupt discontinuation, recommend medical review for chronic users, favor cognitive behavioral therapy for insomnia over routine long-term melatonin, and call for prospective trials to clarify heart safety.