No 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.
What the study found
No randomised trial has tested a year of melatonin on the heart
The longest of 37 randomised sleep trials ran 29 weeks, and those in heart patients stopped at 24 weeks. No genetic study of melatonin itself and heart disease has been found either. What a year or more of nightly melatonin does to the heart has never been tested in a randomised trial.
The caveat · Few registered trials posted results
The trial registry lists two melatonin trials in heart failure, one withdrawn and one with no update since 2020.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.