A recent study has raised concerns about the potential impact of prolonged melatonin use on heart health, particularly for individuals suffering from chronic insomnia. The research, which analyzed medical records of over 130,000 people, found that those who took melatonin for 12 months or more had a significantly higher chance of developing heart failure.
Melatonin, often referred to as the "sleep hormone," plays a role in regulating the body's natural sleep-wake cycle, known as the circadian rhythm. While it is generally considered safe for short-term use and may help some individuals fall asleep faster, its long-term effects have been less clear.
Study Findings
The study, presented at the American Heart Association’s Scientific Sessions 2025, examined five years of medical data from 130,828 individuals diagnosed with insomnia. The findings indicated that patients prescribed and taking melatonin for a year or longer were approximately 90% more likely to experience heart failure over a five-year period compared to those who did not use the supplement. The research also linked extended melatonin use to hospitalization for heart failure and an increased risk of death from any cause in this specific group.
Heart failure is a condition where the heart cannot pump blood effectively enough to meet the body's demands. While manageable for many, it can lead to serious complications, including abnormal heart rhythms, liver damage, and, in severe cases, death.
Dr. Ekenedilichukwu Nnadi, a lead author of the study, stated that these findings suggest melatonin supplements may not be as harmless as commonly believed. He noted that if confirmed, these results could influence how healthcare providers advise patients on sleep aids.
Nuances and Further Research
Researchers emphasized that the study establishes an association and does not definitively prove that melatonin causes heart problems. They highlighted the need for further research to confirm these findings and explore the potential causal relationship.
One of the key considerations raised by the study is the possibility of a "chicken-and-egg" scenario. Dr. Salma Patel, a sleep medicine specialist not affiliated with the study, questioned whether melatonin use contributes to cardiovascular risk or if it indicates a subgroup of patients with more complex underlying sleep or medical issues who are more likely to use sleep aids.
The need for consistent use of sleep aids might signal an unaddressed underlying health problem contributing to insomnia. Nnadi suggested that individuals with more severe insomnia, depression, anxiety, or other conditions may be more prone to using melatonin and could have independent cardiovascular risk factors.
He also pointed out that other factors like worse insomnia severity, co-occurring mental health conditions, or the use of other sleep-enhancing medications might be linked to both melatonin use and heart risk. However, the study cannot prove a direct cause-and-effect relationship.
Broader Sleep Health Considerations
Patel noted that sleep disturbances can stem from various conditions beyond insomnia, including sleep apnea, circadian rhythm disorders, restless legs syndrome, and psychiatric or medical conditions, all of which can coexist with insomnia and may have their own cardiovascular implications.
She advised that for individuals who find themselves relying on melatonin nightly for extended periods, it is beneficial to investigate the underlying reasons for persistent sleep difficulties. Such an evaluation could identify chronic insomnia disorder or other contributing factors like sleep disorders, circadian issues, medical or psychiatric conditions, or medication side effects.
For those diagnosed with chronic insomnia disorder, Cognitive Behavioral Therapy for Insomnia (CBT-I) is considered the gold standard treatment. CBT-I focuses on addressing the thoughts and behaviors that disrupt sleep, helping individuals cultivate healthier sleep habits rather than solely treating sleeplessness.