Could Your Sleep Aid Double Mortality Rates?

That nighttime melatonin pill millions trust for better sleep may carry a cardiovascular risk serious enough to make your cardiologist raise an eyebrow.

Story Snapshot

Study of over 130,000 adults links long-term melatonin use to 90% higher heart failure risk and doubled mortality rates over five years
Chronic users faced 3.5 times higher hospitalization rates for heart failure compared to non-users, challenging melatonin’s “safe and natural” reputation
Research presented at American Heart Association 2025 sessions remains preliminary and shows association, not proven causation
Experts urge randomized clinical trials to confirm findings and investigate mechanisms behind unexpected cardiovascular outcomes

The Bedtime Routine Under Scrutiny

Dr. Ekenedilichukwu Nnadi stood before colleagues at the American Heart Association’s Scientific Sessions in Dallas this past November with data that disrupted decades of conventional wisdom. His team analyzed multinational electronic health records from over 130,000 insomnia patients, average age 56, tracking outcomes over five years. The results revealed a hazard ratio of 1.89 for incident heart failure among those using melatonin for a year or longer. That translates to an alarming 90% increased risk compared to matched non-users. Even more concerning, all-cause mortality doubled with a hazard ratio of 2.09.

The hospitalization data painted an equally stark picture. Chronic melatonin users landed in hospitals for heart failure at rates approaching 19%, while their non-using counterparts hovered between 6.6% and 7%. That 3.5-fold difference persisted even after researchers adjusted for age, existing heart conditions, depression, and anxiety. The consistency across sensitivity analyses, which verified findings among users with at least two prescription fills spaced 90 days apart, made the patterns harder to dismiss as statistical noise. Nnadi emphasized the study reveals association, not causation, but called the cardiovascular signals too striking to ignore.

From Natural Remedy to Question Mark

Melatonin entered the American supplement market in the 1990s marketed as a natural hormone that regulates sleep-wake cycles. Its over-the-counter status in the United States, contrasting with prescription-only access in the United Kingdom, fueled a multi-billion dollar industry built on the promise of gentle, side-effect-free slumber. Prior research catalogued mild concerns like morning drowsiness, vivid dreams, and rare fracture risk in elderly populations. The Mayo Clinic consistently rated short-term use as generally safe while acknowledging a vacuum of long-term cardiovascular data. That knowledge gap motivated Nnadi’s team to mine the TriNetX database for real-world patterns among chronic insomnia sufferers.

The supplement industry thrived on melatonin’s reputation as benign, a sleep solution free from the dependency risks of prescription sedatives. Global insomnia prevalence sits around 16%, creating enormous demand for accessible alternatives. Researchers found no large-scale studies connecting prolonged melatonin use to severe outcomes like heart failure or mortality before this analysis. The 2025 findings clash sharply with earlier work reporting high-dose tolerance, even at 40 milligrams or more, in certain patient populations. That disconnect between past safety profiles and current cardiovascular signals underscores why experts demand rigorous randomized controlled trials to resolve the uncertainty.

Expert Voices and Unanswered Questions

Cardiologist Puja Mody described the consistency of adverse outcomes across the study’s subgroups as noteworthy enough to warrant randomized trials exploring biological mechanisms. Sleep specialist Dr. Yu-Ming Ni recommended patients cap doses at one to three milligrams taken one to two hours before bed, reflecting caution rather than panic. Nnadi acknowledged possible confounders, particularly that severe insomnia itself correlates with cardiovascular disease and mortality. Depression and anxiety, common in chronic insomnia patients, compound the challenge of isolating melatonin’s independent effects. The observational design cannot rule out residual confounding, leaving open the possibility that sicker patients gravitate toward melatonin rather than melatonin causing deterioration.

The research awaits peer review and formal publication, a critical step before regulatory bodies like the FDA might consider labeling changes or advisories. Media coverage amplified the findings through outlets ranging from Medical News Today to NBC, sparking public inquiries to physicians about switching sleep strategies. The American Heart Association and American College of Cardiology amplified the presentation through press releases, framing the data as a call for deeper investigation rather than immediate alarm. No industry funding appeared in the disclosures, though the over-the-counter status of melatonin limits regulatory oversight compared to prescription medications. The supplement market exceeding two billion dollars pre-2025 faces pressure to fund safety trials that could reshape its most popular product.

What Chronic Users Should Consider

The short-term implications ripple through clinical practice as physicians field questions from long-term users weighing benefits against newly visible risks. Insomnia patients, particularly those over 40, confront informed consent discussions that were absent when melatonin felt consequence-free. Sleep medicine specialists face the challenge of balancing patient autonomy with emerging cardiovascular concerns that remain unproven by gold-standard randomized trials. The debate hinges on whether severe insomnia, known to independently elevate heart failure and mortality risk, confounds the observed associations or whether melatonin exerts direct harmful effects on cardiac function through mechanisms not yet understood.

Long-term consequences depend entirely on whether future randomized controlled trials confirm causation. If melatonin directly contributes to heart failure, guidelines will shift toward stricter dosing limits, duration caps, and enhanced screening for at-risk populations. Alternatives like cognitive behavioral therapy for insomnia, prescription sleep aids with established cardiovascular profiles, or non-pharmacological interventions could gain preference. Regulatory scrutiny might impose labeling requirements warning chronic users of cardiovascular monitoring, particularly for those with existing heart conditions or risk factors. The economic impact could dent supplement sales if consumer confidence erodes, while the social backlash against “natural equals safe” marketing may extend beyond melatonin to broader supplement categories lacking rigorous long-term safety data.