Long-Term Melatonin Use: Unpacking a Potential Link to Increased Heart Failure Risk

January 25, 2026

A recent comprehensive observational study, published in early 2025 in the esteemed Journal of the American College of Cardiology: Advances, has brought to light a significant association. The research indicates that consistent, long-term use of melatonin supplements (defined as three or more years of regular intake) may be connected to a slightly elevated risk of hospitalization due to heart failure among adults aged 50 and above.

Key Insights from the Study Findings

• Study Population: The research involved approximately 250,000 adults, with an average age of 58. Participants were monitored for a median duration of 7.2 years, utilizing commercial claims data from the U.S. spanning 2015 to 2022.
• Defining Exposure: Long-term melatonin exposure was identified by individuals having filled at least three melatonin prescriptions over a period of 90 days or more within any given 365-day cycle.
• Primary Outcome Measured: The study primarily focused on the occurrence of a patient’s first hospitalization for heart failure.
• Adjusted Risk Ratio: For individuals engaging in long-term melatonin use compared to non-users, the adjusted hazard ratio (HR) was reported as 1.14 (with a 95% confidence interval of 1.06–1.23).
• Absolute Risk Difference: While statistically significant, the absolute increase in risk was modest, translating to roughly 0.8 additional heart failure events per 1,000 person-years.
• Increased Vulnerability: A more pronounced correlation was observed in individuals who already presented with pre-existing cardiovascular risk factors, such as hypertension, diabetes, or a history of myocardial infarction (heart attack).
• Robustness of Association: The observed link persisted even after meticulous adjustments for various factors, including age, sex, co-existing medical conditions, the use of other sleep aids, and employing propensity-score matching techniques.

Important Limitations and Considerations Highlighted by Researchers

Both the study authors and editorial reviewers underscored several critical limitations inherent in the research design:

• Observational Design: As an observational study, it can only demonstrate an association, not definitively prove a cause-and-effect relationship between melatonin use and heart failure.
• Potential for Confounding by Indication: It is highly probable that individuals who take melatonin for extended periods often suffer from underlying health issues like chronic insomnia, sleep apnea, engage in shift work, or experience anxiety/depression. These conditions are known to independently elevate the risk of heart failure, potentially confounding the results.
• Dosage Data Gaps: The study lacked comprehensive data on specific melatonin dosages. While most prescriptions ranged from 3 to 10 mg, higher recreational doses, often used without medical oversight, were not captured.
• Underestimation of OTC Use: Data on over-the-counter (OTC) melatonin use was unavailable, suggesting that the actual prevalence of melatonin exposure might be significantly underestimated.
• Unaccounted Sleep Apnea Severity: The study did not adjust for the severity of sleep apnea, a major risk factor for heart failure and a common reason individuals turn to melatonin.
• Limited Follow-up Duration: Given that heart failure is a slow-progressing condition, the median follow-up period of 7.2 years might be considered relatively short to fully capture long-term effects.
• Absence of Clear Biological Mechanism: The paper did not identify a definitive biological mechanism explaining the observed association. Authors offered speculative hypotheses, suggesting possible impacts on blood pressure rhythm, inflammation, or autonomic nervous system function, all of which remain theoretical.

Insights from Other Recent Research (2023–2025)

To provide a broader context, it’s beneficial to consider other contemporary evidence regarding melatonin’s effects:

• Short-Term Clinical Trials: Studies lasting from weeks to months generally indicate that melatonin either has a neutral effect or offers slight benefits concerning blood pressure and endothelial function in individuals with hypertension or metabolic syndrome.
• Animal Studies: Research in animal models presents a mixed picture. Some studies suggest melatonin may offer protective effects against cardiac remodeling, while others hint that high doses could potentially impair mitochondrial function.
• Lack of Large-Scale RCTs: Crucially, no extensive randomized controlled trial (RCT) has ever been conducted specifically to evaluate the long-term risk of heart failure associated with melatonin use.
• European Registry Data: Several European registries, compiling data in 2024, have not reported a clear signal for an increased heart failure risk when melatonin is used at typical over-the-counter doses (1–5 mg).

Current Expert Consensus (as of Mid-2025)

As of mid-2025, leading cardiology and sleep medicine organizations, including the American Heart Association (AHA), the European Society of Cardiology (ESC), and the American Academy of Sleep Medicine (AASM), have not revised their official guidelines concerning melatonin based solely on this observational study. These prominent societies continue to affirm that melatonin generally possesses a favorable safety profile for short- to medium-term use in managing insomnia, jet lag, and certain circadian rhythm disorders, particularly when administered at physiological doses (0.5–5 mg).

Nonetheless, many cardiologists are now advising patients on long-term melatonin use (exceeding 6–12 months) with the following practical recommendations:

• Utilize the Lowest Effective Dose: Often, doses between 0.5 and 3 mg are sufficient for initiating sleep.
• Consider Prolonged-Release Formulations: If available, these formulations can better mimic the body’s natural melatonin rhythm.
• Periodically Reassess Necessity: Many individuals may find it possible to gradually reduce or discontinue melatonin once their sleep hygiene practices have been optimized.
• Monitor Cardiac Health: Patients, especially those with pre-existing heart failure, reduced ejection fraction, or multiple cardiovascular risk factors, should regularly monitor their blood pressure and any emerging heart failure symptoms.

Guidance for Individuals Over 60

For the majority of adults over the age of 60, occasional or short-term melatonin use (spanning a few weeks to several months) at lower doses remains among the safest available options for sleep support.

Conversely, chronic daily melatonin use extending over years, particularly at higher dosages (5–10 mg or more), is associated with a scarcity of long-term safety data. Such prolonged, higher-dose use may potentially carry a small, elevated risk of heart failure, especially for individuals already identified as having increased cardiovascular vulnerability.

If you are currently using melatonin on a long-term basis, it is highly advisable to discuss this with your cardiologist or primary care physician during your next medical appointment. They can assess your individual circumstances and, if appropriate, might suggest a trial reduction in dosage or explore alternative strategies for sleep management, such as Cognitive Behavioral Therapy for Insomnia (CBT-I), low-dose trazodone, or mirtazapine. Sometimes, even a minor adjustment in dose or duration can significantly impact long-term safety and overall well-being.

Disclaimer

This article is intended strictly for informational purposes and should not be construed as medical advice. It is imperative that you never discontinue, commence, or modify any supplement or medication, including melatonin, without explicit consultation with your prescribing physician or cardiologist. The risk of heart failure is a complex issue influenced by numerous factors, and melatonin represents only a very small component of this intricate picture. Should you experience any concerning cardiac symptoms such as shortness of breath, leg swelling, persistent fatigue, rapid weight gain, or any other alarming signs, seek immediate medical attention. Personalized medical guidance tailored to your specific health profile is absolutely essential.