Long-term use of the popular melatonin sleep aid could be a sign of higher risk of heart failure and early death in adults with insomnia. The study team said while there no evidence that melatonin supplements themselves cause heart problems, a need to take them on a regular basis to help with sleep could be a signal that the body is experiencing cardiac issues.
“Insomnia can increase blood pressure, stress hormones and inflammation,” said Dr Ekenedilichukwu Nnadi, lead author of the study and an internal medicine resident at SUNY Downstate/Kings County Primary Care in New York City, according to NBS News.
Nnadi and colleagues looked at five years of electronic health records from 130 828 adults, average age 56, finding that people who took melatonin regularly for at least a year were nearly twice as likely to develop heart failure as those who didn’t use the supplement, though the actual rates were relatively low: 4.6% of people in the melatonin group developed heart failure, compared with 2.7% among those who didn’t take melatonin.
They were more than three times as likely to be hospitalised for the condition (19% versus 6.6%), and nearly twice as likely to die during the study period, compared with people who didn’t take melatonin regularly.
It’s unclear, however, whether the data captured outcomes of all people in the US who take melatonin long term. Researchers identified people as chronic users of melatonin based on medical records only – that is, if they’d been prescribed the supplement. In America, the supplement is available over the counter and isn’t often reflected in medical records.
“I caution people against drawing concrete conclusions based on this study alone,” said Dr Nishant Shah, a preventive cardiologist at Duke University Medical Centre, North Carolina, who wasn’t involved with the study.
“But now that we have this observation, this is prime time to figure out whether there’s actually a direct association of harm with sleep agents. That would be practice-changing.”
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.
While the study found that long-term melatonin use was an indicator of potential heart problems – and not causing the problems itself – experts agreed more research is needed into the supplements’ possible side effects.
“We have patients using all kinds of supplements without understanding the risks,” said Dr Martha Gulati, a preventive cardiologist and the incoming director of the Davis Women’s Heart Centre at Houston Methodist DeBakey Heart and Vascular Institute in Texas.
“If there is harm from a supplement, it means the cost could be far more than simply expensive urine.” Gulati was not involved with the new study.
Melatonin is a hormone made naturally by the body that helps regulate sleep and wake cycles. Synthetic versions, sold widely over the counter as dietary supplements, are marketed to help people fall asleep faster or overcome jet lag. Because supplements aren’t regulated by the US Food and Drug Administration (FDA), doses and purity can vary widely among brands.
Use of the supplement has increased in recent years. A 2022 Sleep Foundation survey found that up to 27% of US adults take melatonin, as well as 4% of kids.
The new study didn’t include children.
NBC News article – What taking melatonin could reveal about your heart health (Open access)
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