'Night owl' lifestyle may bring higher risk of heart disease: Study
So-called "night owls" may face a higher risk for heart attack and stroke, a new study published Wednesday finds.
Researchers found that "evening type" people had poorer cardiovascular health scores than those who were neither "morning type" or "evening type" people and had an associated 16% higher risk of heart attack and stroke.
The study, published in the Journal of the American Heart Association, analyzed survey and biometric data from more than 320,000 British adults aged 39 to 74.
Participants were asked whether they considered themselves a "definite morning" person, a "definite evening" person or somewhere in between, termed "intermediate."
Researchers then calculated each person's heart health using the American Heart Association's Life's Essential 8 (LE8) score. These factors include four health behaviors -- diet quality, physical activity, sleep duration and nicotine exposure -- and four health factors, including blood pressure, body mass index, blood sugar and blood fat levels.
"These are the factors the American Heart Association has identified as cardiovascular disease risk factors," Kristen Knutson, associate professor of neurology and peventive medicine at Northwestern University Feinberg School of Medicine specializing in sleep and circadian rhythm research and fellow at the American Heart Association, told ABC News.
"Different people will have them in different combinations, but they are all correlated with one another," she added.
Evening people were 79% more likely to have poor overall heart health compared with those in the intermediate group, the study found. Morning people did slightly better than the intermediate group, with a 5% lower risk of having a poor LE8 score.
Researchers found the evening people had a 16% higher risk of both heart attack and stroke. Researchers estimated that about 75% of this higher risk was explained by other LE8 factors, rather than sleep timing alone.
"It isn't being a night owl that's a problem," Knutson said. "I think being a night owl who's trying to live in a morning lark's world is a conflict between one's internal clock and their social clock."
The higher risk appeared to be due to certain lifestyle behaviors and other health factors, the study found.
Nicotine use had the strongest impact on heart health, explaining 34% of the link between late bedtime and heart disease. Shorter sleep duration accounted for 14% of the extra risk, high blood sugar for 12% and body weight and diet each accounted for about 11% of the increased risk.
Behavioral effects of being a night owl were stronger in women than in men -- women were 96% more likely to have lower LE8 scores compared to 67% in men, though they did not have a higher risk of heart attack or stroke.
"Women are further stressed by that lifestyle because they're having to still get up and be the primary caregiver for family members," Dr. Sonia Tolani, preventative cardiologist, Associate Professor of Medicine, and co-director of the Columbia University Women's Heart Center, told ABC News.
Heart disease remains the leading cause of death in the U.S., according to the Centers for Disease Control and Prevention. The researchers concluded prevention efforts should focus on improving lifestyle habits when spending more time awake at night.
"The most obvious way is to quit smoking and that's not new advice," Knutson says. "But sleep regularity, meaning trying to go to bed at about the same time every day and not jumping around the clock -- particularly on days off -- can really help lead to regular timing of other behaviors like light exposure, meals, exercise activity."
"Prioritize the low-hanging fruit" recommended Tolani. If an hour at the gym is not doable, "maybe you can find a way to do a 10-minute walk or cut a little bit of salt from your diet. Just try to make small changes," she said.
Dr. Joseph Wendt is a public health and preventive medicine resident at Icahn School of Medicine at Mount Sinai and a member of the ABC News Medical Unit.
