Taking melatonin for long periods could be a sign of underlying heart problems.
Long-term use of the popular over-the-counter sleep aid has been linked to an increased risk of heart failure and premature death in adults with insomnia, according to research published Monday.
There is no evidence that melatonin supplements themselves cause heart problems, the researchers said. But the need to take them regularly to help you fall asleep and stay asleep could be a sign that the body is experiencing heart problems.
“Insomnia can increase blood pressure, stress hormones and inflammation,” said Dr. Ekenedilichukwu Nnadi, lead author of the new study and an internal medicine resident at SUNY Downstate/Kings County Primary Care in New York City.
Nnadi and his colleagues looked at five years of electronic medical records from 130,828 adults, with an average age of 56, and found that people who took melatonin regularly for at least a year were almost twice as likely to develop heart failure compared to those who did not use the supplement, although the actual rates were relatively low: 4.6% of people in the melatonin group developed heart failure, compared with 2.7% among those who did not take melatonin.
They were more than three times more likely to be hospitalized for the condition (19% vs. 6.6%) and almost twice as likely to die during the study period, compared to people who did not take melatonin regularly.
However, it is not clear whether the data captured the results of all people in the US who take melatonin long-term. The researchers identified people as chronic melatonin users based solely on medical records—that is, whether they had been prescribed the supplement. In the US, the supplement is available without a prescription and is not typically reflected in medical records.
“I caution people not to draw any concrete conclusions based solely on this study,” said Dr. Nishant Shah, a preventive cardiologist at Duke University Medical Center in Durham, North Carolina, who was not involved in the study. “But now that we have this observation, it’s the best time to determine whether there really is a direct association of harm with sleep agents. That would change practice.”
Nnadi’s research is scheduled to be presented in New Orleans at an upcoming meeting of the American Heart Association. It has not been published in a peer-reviewed journal.
Heart failure occurs when the heart cannot pump enough oxygen-rich blood to the body’s organs for them to function properly. Nearly 7 million Americans have this condition, according to the Centers for Disease Control and Prevention.
While the study found that long-term melatonin use was an indicator of possible heart problems (and did not cause the problems themselves), experts agreed that more research is needed on the possible side effects of the supplements.
“We have patients using all types of supplements without understanding the risks,” said Dr. Martha Gulati, a preventive cardiologist and incoming director of the Davis Women’s Heart Center at Houston Methodist DeBakey Heart and Vascular Institute in Texas. “If a supplement causes harm, it means the cost could be much more than just expensive urine.” Gulati was not involved in the new study.
Melatonin is a hormone produced naturally by the body that helps regulate sleep and wake cycles. Synthetic versions, widely sold over the counter as dietary supplements, are marketed to help people fall asleep faster or overcome jet lag. Because supplements are not regulated by the Food and Drug Administration, dosages and purity can vary widely between brands.
Use of the supplement has increased in recent years. A 2022 survey from the Sleep Foundation found that up to 27% of American adults take melatonin, as well as 4% of children. The new study did not include children.
People who take melatonin for sleep for more than a year should talk to their doctor, experts said.
“People should be aware that it should not be taken chronically without proper indication,” Marie-Pierre St-Onge, director of the Center of Excellence for Circadian and Sleep Research at Columbia University Irving Medical Center in New York, said in a news release. St-Onge was not involved in the new investigation.
