Heart Failure Risk Higher With Long-Term Melatonin, Study Finds

Written by Ted Samson

Posted on January 14, 2026

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A large study of adults with chronic insomnia (difficulty sleeping) found that those who used melatonin for a year or longer were more likely to be diagnosed with heart failure, be hospitalized for the condition, or die from any cause over five years, compared with people who did not use melatonin.

🗳️ How often do you use melatonin to help with sleep?

Most nights

Occasionally

Rarely

Never

“If you’re using [melatonin] indefinitely, especially if you have heart disease or risk factors, it’s something worth discussing with your physician,” said Dr. Ekenedilichukwu Nnadi, lead study author and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care, in an interview with Medscape Medical News.

What Is Melatonin?

Melatonin is a hormone your body makes to help control your sleep-wake cycle. Levels rise at night when it’s dark and fall during the day. Because of this role, melatonin supplements are commonly used to help with insomnia or jet lag.

In the United States and many other countries, melatonin is sold over the counter and often viewed as a “natural” and harmless sleep aid. However, supplements aren’t regulated as strictly as prescription medications, which means their strength and purity can vary among brands.

According to the Sleep Foundation, past studies suggested that short-term melatonin use is safe for most adults, but research on long-term safety is limited.

What the Study Found

Researchers reviewed electronic health records from more than 130,000 adults diagnosed with chronic insomnia. About half had documented long-term melatonin use, defined as taking the supplement for at least one year. These individuals were compared with similar adults who had insomnia but no record of melatonin use. The researchers found that:

People using melatonin long term had about a 90 percent higher risk of heart failure than those who didn’t use the supplement (4.6 percent versus 2.7 percent).
People taking melatonin were almost 3.5 times more likely to be hospitalized for heart failure.
People in the melatonin group were nearly twice as likely to die from any cause during the five-year study period.

The increased risks remained even after the researchers adjusted for many health factors, such as age, sex, blood pressure, body mass index, and existing heart or nervous system conditions.

It’s important to note that this type of study shows an association, not cause and effect. The findings don’t prove that melatonin directly causes heart failure. Other factors — such as more severe sleep problems or underlying health conditions — may also play a role.

Why This Matters for People With Heart Disease

Sleep problems are common among people living with heart conditions, including heart failure. A 2021 study found that 45 percent of 488 people with coronary heart disease experienced insomnia. Many people turn to melatonin because it’s easy to access and widely considered safe. This study raises important questions about whether long-term use is as harmless as many assume, especially for people already at higher risk of heart problems.

The researchers emphasized that more studies are needed to understand whether melatonin itself affects heart health or if the increased risk is related to other factors. Still, the findings suggest that long-term use should not be taken lightly.

If you have heart disease and have trouble sleeping, it may help to talk with your healthcare provider before starting or continuing melatonin long term. Together, you can discuss other ways to manage sleep issues that fit your overall heart health plan.