Long-term melatonin use may raise heart failure risk by 90%: Study

A major global study presented at the American Heart Association's 2025 Scientific Sessions links long-term melatonin use to a 90% higher risk of heart failure and nearly double the death rate

Long-term use of melatonin supplements may sharply raise the risk of heart failure and even death, according to a major new global study.

 

Presented at the ongoing American Heart Association’s Scientific Sessions 2025 in New Orleans, the research tracked over 130,000 adults with insomnia worldwide for five years and found that those who took melatonin for more than a year had a 90 per cent higher chance of developing heart failure and were nearly twice as likely to die from any cause over the next five years compared with non-users.

Is your nightly melatonin habit putting your heart at risk?

According to the statement released by the American Heart Association, the research, led by Dr Ekenedilichukwu Nnadi of SUNY Downstate/Kings County Primary Care, has sparked a major rethink about the safety of one of the world’s most popular sleep aids.

 

The study compared adults diagnosed with insomnia who used melatonin for at least a year with those who never took it. “Among adults with insomnia, those whose electronic health records indicated long-term melatonin use (12 months or more) had about a 90 per cent higher chance of incident heart failure over five years compared with matched non-users,” the statement said.

 

Even more concerning, 19 per cent of long-term melatonin users were hospitalised for heart failure, compared to 6.6 per cent of non-users. The death rate among regular users was also almost double at 7.8 per cent versus 4.3 per cent.

 

Researchers found these risks remained high even after adjusting for factors such as age, sex, existing health conditions, and medications.

Why could melatonin affect the heart?

Melatonin is a hormone naturally produced by the brain’s pineal gland at night to regulate the sleep-wake cycle. But synthetic versions sold over the counter may not mirror the body’s natural rhythm.

 

Dr Nnadi explained in the statement that many supplements contain doses 10 times higher than what the body naturally produces, and their labels are often inaccurate. This mismatch, scientists believe, could interfere with the body’s cardiovascular and metabolic balance.

Why are experts concerned about melatonin misuse?

Unlike prescription sleep aids, melatonin is available over the counter in most countries, including India. It is often perceived as “natural” and therefore harmless. But scientists warn that’s a dangerous misconception.

 

“I’m surprised that physicians would prescribe melatonin for more than a year. In the US, melatonin isn’t even approved for insomnia treatment — it’s meant for short-term use, like jet lag,” said Dr Marie-Pierre St-Onge, Professor of Nutritional Medicine at Columbia University and Chair of the American Heart Association’s 2025 Scientific Statement on Sleep Health.

Should you stop taking melatonin?

Experts advise against abruptly stopping melatonin if you have been taking it regularly, but they recommend speaking to a doctor about safer alternatives.

 

The researchers highlighted that melatonin use has skyrocketed in the past decade, with millions of adults and children taking it regularly. With increases in stress, erratic schedules, and screen time, normal sleep patterns have been disrupted, leading many to rely on melatonin as a “quick fix”, unaware of its potential long-term effects.

 

Dr St-Onge said, “Melatonin should not be taken chronically without a proper indication. People need to prioritise sleep hygiene and focus on consistent sleep schedules, limiting caffeine, reducing screen time, and creating a dark, cool sleeping environment.”

 

For those with chronic insomnia, cognitive behavioural therapy (CBT-I) remains the most effective non-drug treatment. 

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