People who naturally prefer late nights may be putting their heart health at greater risk than early risers, according to new research—but experts say lifestyle changes can significantly reduce that danger.
A large study published Wednesday in the Journal of the American Heart Association found that adults who identify as “night owls” were more likely to have poorer overall heart health and a higher long-term risk of heart attacks and strokes compared with people who follow earlier or more traditional sleep schedules. The association was especially pronounced among women.
Inside the Research
The study analyzed data from nearly 323,000 adults enrolled in the UK Biobank, a long-running health research project. Participants, whose average age was 57, reported their natural sleep preferences, known as chronotypes—whether they function best in the morning, evening, or somewhere in between.
Researchers then assessed participants’ cardiovascular health using the American Heart Association’s “Life’s Essential 8” framework, which measures key factors such as sleep quality, physical activity, diet, weight, smoking, blood pressure, cholesterol, and blood sugar.
About two-thirds of participants fell into the intermediate group, while 24% identified as morning people and 8% as evening types.
Higher Risk for Late-Night Types
On average, participants scored 67 out of 100 on heart health. Women generally scored higher than men. But compared with those in the intermediate group, night owls were far more likely to have poor cardiovascular health scores.
Researchers found that night owls had a 79% higher prevalence of poor heart health, defined as a score below 50. Over a median follow-up of 14 years, they also faced a 16% higher risk of heart attacks or strokes. Early risers did not show an increased risk.
The strongest links between late-night schedules and poor heart health were tied to sleep quality and nicotine use, though night owls also scored lower across several other health measures.
Why Sleep Timing Matters
Experts say the findings add to growing evidence that circadian rhythm—how well a person’s internal clock aligns with daily routines—plays a significant role in cardiovascular health.
Sleep is critical for regulating stress hormones, metabolism, and tissue repair. Chronic sleep disruption or misalignment can elevate cortisol levels, increase inflammation, and contribute to long-term heart disease.
The American Heart Association recommends adults get seven to nine hours of quality sleep per night, noting that both insufficient and excessive sleep are linked to cardiovascular problems.
Not a Life Sentence for Night Owls
Cardiologists and sleep specialists emphasize that being a night owl does not doom someone to heart disease. The increased risks observed in the study were modest and largely tied to behaviors that can be changed.
Healthy habits—such as quitting smoking, exercising regularly, maintaining a balanced diet, and prioritizing consistent sleep—can significantly offset the risks associated with late-night chronotypes.
Experts also recommend limiting late-night eating, reducing caffeine intake well before bedtime, and managing light exposure by getting bright light in the morning and dimming lights in the evening to support natural melatonin production.
Study Limitations and What’s Next
The researchers noted several limitations, including reliance on self-reported sleep preferences and a study population that was mostly white and middle-aged or older. Heart health measures were also assessed at a single point in time.
Further research is underway to explore genetic factors behind chronotypes and to better understand why the link between late-night habits and heart health appears stronger in women.
Sleep specialists stress that delayed sleep patterns are not a flaw or a sign of laziness—but a biological difference that can be managed.
“Night owls aren’t broken,” one expert noted. “Their rhythm is just different—and with the right habits, they can still protect their heart.”
