Being a night owl may feel productive — even energising — but new research suggests it could come with hidden costs for heart health. A large long-term study has found that people who are most active late at night tend to have poorer cardiovascular health than those with earlier or more average daily rhythms.
The findings, published in the Journal of the American Heart Association, draw on data from more than 300,000 middle-aged and older adults tracked through the UK Biobank over 14 years. Around eight per cent of participants identified as night owls, while roughly a quarter were early risers. The rest fell somewhere in between.
Researchers found that night owls had a 16 per cent higher risk of experiencing a first heart attack or stroke compared to the average population. They were also less likely to meet the American Heart Association’s eight key benchmarks for heart health, which include physical activity, sleep, diet, weight management and avoiding tobacco.
The issue, experts say, is not staying up late in itself, but the mismatch between a person’s internal clock and the structure of daily life. Most work and social schedules are designed for morning-oriented routines, forcing night owls to wake earlier than their bodies naturally prefer.
That misalignment can influence behaviour. Night owls in the study were more likely to smoke, sleep less and make poorer dietary choices — all well-established risk factors for heart disease. Metabolism also follows a daily rhythm, meaning the body may process food less efficiently at certain times, particularly very early in the day.
Heart disease remains the leading cause of death in the United States, and similar patterns are seen globally. The good news, researchers stress, is that risk is not fixed. Maintaining regular sleep and wake times, even without hitting ideal sleep durations, can help. So can prioritising physical activity, eating balanced meals and, most importantly, quitting smoking.
As one researcher put it, the goal is not perfection. For night owls and early birds alike, focusing on basic, consistent health habits may matter far more than the hour on the clock.
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