How Being a Night Owl Can Impact Cardiovascular Health

We all have a natural body clock, with an individual often being described as either a morning person or a night owl. A study published in the Journal of the American Heart Association looked at whether that natural preference for earlier or later schedules is linked to heart disease risk and, if so, why.

A team of investigators followed more than 322,000 adults in the U.K. for nearly 14 years. None had heart disease at the start of the study. Participants reported their chronotype (morning, intermediate or evening) and investigators tracked who went on to have a heart attack or stroke. They also calculated each person’s Life’s Essential 8 (LE8) score, a measure of heart health that includes factors like diet, physical activity, sleep, blood pressure, cholesterol, blood sugar, smoking and body weight.

Among participants, 8% were self-reported “definitely evening people,” defined as having a late-night bedtime (for example, 2 a.m.) and activity peaks later in the day. Approximately 24% were “definitely morning people,” while 67% were in the “intermediate” chronotype.

The findings showed that people who identified as definite evening types were much more likely to have poorer overall heart health. Compared with people who had an intermediate chronotype, evening types were 79% more likely to have a low LE8 score, meaning they had more cardiovascular risk factors overall.

“‘Evening people’ often experience circadian misalignment, meaning their internal body clock may not match the natural day-to-night light cycle or their typical daily schedules,” said lead investigator Sina Kianersi, Ph.D., D.V.M., a research fellow in the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital and Harvard Medical School. “Evening people may be more likely to have behaviors that can affect cardiovascular health, such as poorer diet quality, smoking and inadequate or irregular sleep.”

Over time, evening chronotypes also had a higher risk of developing cardiovascular disease, including heart attacks and strokes. This particularly impacts middle-aged and older adults, especially women. Importantly, investigators found that about 75% of this increased risk could be explained by differences in everyday health behaviors and risk factors captured by the LE8 score, not by chronotype alone.

In other words, being a night owl doesn’t automatically cause heart disease. Instead, later sleep schedules may make it harder to maintain heart-healthy habits, such as getting enough sleep, eating well, staying active, and keeping blood pressure and blood sugar in a healthy range.

“These findings show that the higher heart disease risks among evening types are partly due to modifiable behaviors such as smoking and sleep,” said Kristen Knutson, Ph.D., FAHA, volunteer chair of the statement writing group, volunteer chair-elect of the American Heart Association’s Sleep Science Committee and an associate professor of neurology at Northwestern University’s Feinberg School of Medicine in Chicago. “Therefore, evening types have options to improve their cardiovascular health. Evening types aren’t inherently less healthy, but they face challenges that make it particularly important for them to maintain a healthy lifestyle.”

The takeaway for patients is encouraging: Chronotype is not destiny. Even if you naturally prefer late nights, focusing on controllable habits, like consistent sleep timing, regular physical activity, healthy meals, and managing blood pressure and cholesterol, may significantly lower cardiovascular risk.

“Some medications or therapies work best when they align with a specific time of relevant circadian rhythms, and this time will vary depending on whether you are a morning, intermediate or evening chronotype,” Knutson noted. “Targeted programs for people who naturally stay up late could help them improve their lifestyle behaviors and reduce their risk of cardiovascular disease.”