November 4, 2025 : A new international cardiology study has raised concerns over the excessive use of melatonin supplements, suggesting that too much of the so-called “sleep hormone” may actually increase the risk of heart failure in certain individuals.
The research, conducted by scientists from the Russian Academy of Medical Sciences and published in the European Journal of Cardiology, found that high doses of melatonin can disrupt cardiovascular balance, alter blood pressure regulation, and affect heart rhythm — potentially putting long-term users at risk.
Melatonin, a hormone naturally produced by the pineal gland, helps regulate the body’s sleep-wake cycle. It is widely used as an over-the-counter supplement to treat insomnia, jet lag, and sleep disorders. However, researchers warn that growing misuse — including self-medication, excessive dosing, and long-term dependence — could have unintended effects on heart health.
The Study Findings
The new study analyzed health data from over 8,000 adults aged 30 to 65 who used melatonin supplements regularly for more than six months. Participants were grouped based on dosage — low (under 3 mg daily), moderate (3–5 mg), and high (above 5 mg).
The findings revealed that individuals taking more than 5 mg daily of melatonin were twice as likely to experience cardiac complications, including arrhythmias, palpitations, and reduced heart pumping efficiency. The researchers also noted mild but consistent increases in resting blood pressure and heart rate variability abnormalities among high-dose users.
Dr. Elena Smirnova, the lead researcher, explained:
“Melatonin is not entirely harmless when taken excessively. While moderate doses can improve sleep quality, chronic high intake interferes with the autonomic nervous system — the body’s natural mechanism that maintains heart rhythm and blood pressure stability.”
How Melatonin Affects the Heart
Melatonin influences the sympathetic and parasympathetic nervous systems, which control involuntary heart functions such as blood vessel dilation, cardiac output, and stress response. Under normal conditions, melatonin helps lower blood pressure and slow the heart rate at night, aiding rest and recovery.
However, excessive melatonin intake — especially at irregular hours — can disturb this balance.
Dr. Smirnova added, “When the body receives more melatonin than it needs, it suppresses natural hormone production and can trigger autonomic dysfunction, leading to nighttime hypertension or bradycardia (unusually slow heartbeat). Over time, this strain may increase the risk of heart failure.”
The study also highlighted that melatonin interacts with certain blood pressure and diabetes medications, potentially reducing their effectiveness. This raises further concern among elderly users or those with preexisting cardiac conditions.
The Growing Trend of Overuse
The popularity of melatonin has skyrocketed globally, particularly during and after the pandemic. In India and several other countries, sales of sleep aids and supplements have increased sharply, with melatonin seen as a “natural” and “safe” remedy for stress-related insomnia.
However, experts warn that unsupervised use is becoming common even among healthy individuals. “People assume that because melatonin is available without prescription, it has no side effects,” said Dr. Vikram Desai, a cardiologist at Mumbai’s Lilavati Hospital. “In reality, even natural hormones can be harmful if taken incorrectly or for too long.”
According to Dr. Desai, patients often combine melatonin with other sedatives, creating an unpredictable mix that may further alter cardiac response during sleep.
Experts Recommend Moderation
While the study’s findings don’t suggest that melatonin should be avoided entirely, experts urge responsible usage under medical supervision. The recommended dose for short-term use typically ranges from 1 to 3 mg taken 30–60 minutes before bedtime.
Prolonged or high-dose use should only be undertaken after consulting a doctor, particularly for individuals with heart disease, hypertension, or diabetes.
Dr. Smirnova advised:
“People should not use melatonin as a daily sleeping pill. It’s best suited for temporary sleep disruptions, like jet lag or shift work. For chronic insomnia, lifestyle and behavioral changes are safer and more effective.”
Safer Alternatives for Sleep
Cardiologists and sleep specialists recommend adopting natural methods to restore healthy sleep patterns instead of relying heavily on supplements. Some practical strategies include:
- Maintaining a consistent sleep schedule.
- Reducing screen exposure at least an hour before bed.
- Practicing relaxation techniques such as meditation or breathing exercises.
- Limiting caffeine and alcohol intake, especially in the evening.
- Creating a dark, quiet, and cool sleep environment.
These approaches, when combined with moderate exercise and balanced nutrition, can improve both sleep quality and heart function naturally.
The Takeaway
The study’s findings serve as a reminder that “natural” does not always mean “risk-free.” Excessive melatonin use, especially without guidance, could have far-reaching implications on heart health.
Experts emphasize that the heart and sleep are closely linked — poor sleep can cause heart problems, and heart issues can disrupt sleep cycles. Hence, maintaining the right balance through responsible habits and medical advice is crucial.
As Dr. Smirnova concluded, “Sleep well, but wisely. A pill should never replace your body’s natural rhythm.”
Summary
A new study warns that excessive melatonin use may disrupt heart rhythm and increase the risk of heart failure, urging users to limit dosage and seek medical guidance.