People who naturally stay up late tend to think of their night-owl tendencies as a personality quirk or a lifestyle preference. A landmark study published January 28, 2026, in the Journal of the American Heart Association suggests it may also be a cardiovascular risk factor — one that operates over years and compounds with age, particularly in women.
The study, analyzing data from more than 300,000 adults in the UK Biobank, found that people who identified as "definitely evening types" — night owls — had a 79% higher prevalence of overall poor cardiovascular health compared to people with intermediate sleep-wake schedules, and a 16% higher risk of heart attack or stroke over a median follow-up period of about 14 years.
