Middle-aged adults who naturally stay up late are far more likely to have poor cardiovascular health than early risers, according to a major new study published in the Journal of the American Heart Association.
Researchers reviewed health data from more than 300,000 adults in the UK Biobank and found that “night owls” had a 79 per cent higher prevalence of poor cardiovascular health scores compared to those with typical sleep schedules. The study also found that evening types had a 16 per cent higher risk of suffering a heart attack or stroke over the following 14 years.
The findings were particularly pronounced among women, with the “evening” chronotype showing a stronger correlation to low health scores than in men.
Circadian misalignment
The study, led by researchers from Brigham and Women’s Hospital and Harvard Medical School, suggests that the health risks are not inherent to “night owl” biology itself, but rather to the lifestyle that often accompanies it.
“‘Evening people’ often experience circadian misalignment, meaning their internal body clock may not match the natural day-to-night light cycle or their typical daily schedules,” says lead author Dr. Sina Kianersi.
This misalignment often leads to a cluster of unhealthy behaviours. The analysis revealed that much of the increased risk was driven by poor diet, inadequate sleep, and higher rates of smoking among those who stay up late.
Life’s Essential 8
To measure heart health, the researchers used the American Heart Association’s “Life’s Essential 8” checklist.
This metric evaluates eight key components of cardiovascular wellness: diet, physical activity, nicotine exposure, sleep health, body mass index, blood lipids, blood glucose, and blood pressure. While “morning people” (early birds) had a 5 per cent lower prevalence of low scores, night owls consistently scored poorly across these categories.
However, the study offers a silver lining: because the risk is largely driven by behaviour, it can be managed. Kristen Knutson, Ph.D., who was not involved in the study but chairs the Association’s statement on circadian health, emphasised that night owls are not doomed to heart disease.
“These findings show that the higher heart disease risks among evening types are partly due to modifiable behaviours such as smoking and sleep. Therefore, evening types have options to improve their cardiovascular health,” Knutson says. “Evening types aren’t inherently less healthy, but they face challenges that make it particularly important for them to maintain a healthy lifestyle.”
The researchers suggest that targeted health programmes could help night owls align their medication and lifestyle habits with their specific circadian rhythms to mitigate these risks.
