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Is melatonin bad for your heart? No randomised trial has tested a year

No randomised trial has tested a year of nightly melatonin on the heart; sleep trials ran up to 29 weeks. In one gene study, insomnia itself went with 21% higher heart-failure odds.

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Many people now worry that long-term melatonin could cause heart failure. The longest of 37 randomised sleep trials ran 29 weeks and heart-patient trials 24, so a year or more has never been tested on the heart in a randomised trial, and few registered insomnia trials posted results. In one genetic study of 367,586 UK adults, a tendency to insomnia went with 21% higher odds of heart failure; it never looked at melatonin. Comparing users with non-users has to separate the insomnia from the pill.

The findings behind this

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Physical & bodyNo randomised trial has run melatonin for a year to check the heart

Randomised sleep trials ran up to 29 weeks and heart-patient trials up to 24. No randomised trial has tested what a year or more of nightly melatonin does to the heart.

★★★Well replicated — this finding’s sources average out to meta-analyses, systematic reviews or high-powered trials.The trial registry lists two melatonin trials in heart failure, one withdrawn and one with no update since 2020. Of the registered melatonin insomnia trials screened, only 13% had posted results, so some safety data may never have been published.Click to keep this openSupport heart and blood flowMelatonin
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Physical & bodyInsomnia itself may raise your heart-failure risk, gene data suggest

In one genetic study of 367,586 UK adults, an inherited tendency to insomnia went with 21% higher odds of heart failure, even allowing for depression.

★★★Well replicated — this finding’s sources average out to meta-analyses, systematic reviews or high-powered trials.The study measured an inherited tendency to insomnia and never looked at melatonin or any sleep aid. Everyone in it was of European ancestry. About 28% of the people in the insomnia gene data were also in the heart data, which can pull the estimate toward an ordinary association, though the authors judged that bias likely small.Click to keep this openSupport heart and blood flowMelatonin

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