A large study tracking more than 300,000 adults found that those who prefer late nights had poorer cardiovascular health and a higher risk of heart attack and stroke than people who are active earlier in the day.

The effect was particularly pronounced among women.

The analysis focused on chronotypes, which describe a person’s natural preference for sleep and wake timing, and examined how these patterns relate to cardiovascular health.

Much of the elevated risk appeared to stem from lifestyle factors commonly seen among evening types, including smoking and inadequate sleep.

Using data from the UK Biobank, researchers found that night owls were more likely to have lower-quality diets, get too little sleep, and smoke more frequently—habits that helped explain their poorer cardiovascular health scores.

Several notable patterns emerged. Compared with people classified as having an intermediate chronotype, those identified as “evening people,” often referred to as night owls, were 79% more likely to have an overall poor cardiovascular health score.

Night owls also faced a 16% higher risk of experiencing a heart attack or stroke over a median follow-up period of about 14 years.

Writing in the Journal of the American Heart Association, the researchers said the findings highlight a clear opportunity for prevention, noting that improving daily habits such as sleep duration, diet quality, and smoking cessation could help night owls lower their cardiovascular risk.

The association between an evening chronotype and poorer heart health was stronger in women than in men.

Much of the increased risk of heart disease among evening types was linked to lifestyle behaviours, particularly nicotine use and insufficient sleep.

In contrast, “morning people,” also known as early birds, had a 5% lower prevalence of poor cardiovascular health scores compared with individuals without a strong preference for either morning or evening activity.

Kristen Knutson, PhD, FAHA, volunteer chair of the American Heart Association’s 2025 scientific statement, said the findings should not discourage those who prefer late nights.

“Evening types aren’t inherently less healthy,” Knutson explained, “but they face challenges that make it especially important for them to maintain healthy lifestyle habits.” (Nigerian Tribune)

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