Afghanistan, Jan. 31 -- A new study finds that regularly staying up late may increase the risk of heart attack or stroke, especially among night owls.

People who are most active at night and stay up late are more likely to have poor cardiovascular health, the study shows. Night owls face a 16 percent higher risk of heart attack or stroke compared to early risers.

"Evening people often experience circadian misalignment, meaning their internal body clocks do not match natural day-night cycles or daily schedules," said lead author Sina Kianersi of Brigham and Women's Hospital and Harvard Medical School.

The study, published in the Journal of the American Heart Association, analysed more than 300,000 adults, averaging 57 years old, to assess...