Long-term users of melatonin at risk of heart failure: Study

A study presented at the American Heart Association’s scientific meetings has raised concerns about melatonin, one of Britain’s most commonly prescribed sleep aids. The findings suggest that long-term users face a higher risk of heart failure. But the preliminary data demands careful scrutiny before the alarm is sounded. Melatonin has been prescribed in the UK for nearly two decades, with 2.5 million prescriptions issued in England last year alone. The drug is a synthetic version of the hormone naturally produced in the brain – the so-called “hormone of darkness” that regulates our sleep-wake cycle. For years, it’s been considered safe for treating short-term sleep problems in adults and, under specialist supervision, for children with learning disabilities or ADHD. The study, published only as a brief summary, analysed electronic health records of roughly 130,000 adults with sleep difficulties over five years – half of whom took melatonin and half of whom didn’t. People who took melatonin for at least a year were roughly three times more likely to be hospitalised with heart failure than non-users (19 per cent of people who took melatonin versus 6.6 per cent of people who did not). Long-term users also faced higher rates of heart failure diagnosis and death from any cause. The researchers attempted to balance their comparison by matching melatonin users with non-users across 40 factors, including age, health conditions and medications. Yet the study found only an association, not causation. This distinction matters. Correlation doesn’t prove that melatonin caused heart failure.