This may seem surprising, but a large study found that people who are most active late at night (when most of the population is relaxing or already asleep) have worse overall heart health than the average person.
“It’s not that night owls are doomed,” said researcher Sina Kianersi of Brigham and Women’s Hospital and Harvard Medical School, who led the study. “The challenge is the mismatch between the internal clock and typical daily schedules,” which makes it difficult to follow heart-healthy behaviors.
And that has a solution, added Kianersi, who describes himself as “kind of a night owl” who feels a boost in “my analytical thinking” after 7 or 8 p.m.
Heart disease is the leading cause of death in the U.S. The American Heart Association has a list of eight key factors that everyone should pay attention to for better heart health: being more physically active; avoid tobacco; get enough sleep and eat a healthy diet; and control blood pressure, cholesterol, blood sugar and weight.
Where does being a night owl come into play? That has to do with the body’s circadian rhythm, our master biological clock. It follows a roughly 24-hour schedule that regulates not only when we feel sleepy and when we are most awake, but also keeps organ systems in sync, influencing things like heart rate, blood pressure, stress hormones, and metabolism.
Everyone’s circadian rhythm is a little different. Previous research has suggested that night owls may have more health problems, as well as risk factors, such as higher rates of smoking and less physical activity, than people with more typical bedtimes, Kianersi said.
To find out more, Kianersi’s team followed more than 300,000 middle-aged and older adults in the UK Biobank, a huge health database that includes information about people’s sleep and wake preferences. About 8% of those people were classified as night owls, most physically and mentally active in the late afternoon or evening and until after most people’s bedtime. About a quarter were early risers, most productive during daylight hours and also early to bed. The rest were average, somewhere in between.
Over 14 years, night owls had a 16% higher risk of having a first heart attack or stroke compared to the average population, the researchers found.
Night owls, especially women, also had worse overall cardiovascular health based on meeting the eight key heart association factors, researchers reported Wednesday in the Journal of the American Heart Association.
Unhealthy behaviors (smoking, lack of sleep and poor diet) seem to be the main reasons.
“It comes down to the problem of a night owl trying to live in the world of a morning person. They get up early to go to work because that’s when their work starts, but it may not align with their internal rhythm,” said Kristen Knutson of Northwestern University, who led a recent heart association guide on circadian rhythms but was not involved in the new study.
That affects more than sleep. For example, metabolism fluctuates throughout the day as the body produces insulin to convert food into energy. That means it might be harder for a night owl to stomach a high-calorie breakfast eaten very early in the day, during what would normally still be their biological night, Knutson said. And if they go out late at night, it may be harder to find healthy food options.
As for sleep, even if the ideal of at least seven hours can’t be reached, sticking to a regular bedtime and wake-up time can also help, she and Kianersi said.
The study couldn’t examine what night owls do when the rest of the world sleeps. But Kianersi said one of the best measures to protect heart health (for night owls and anyone) is to quit smoking.
“Focus on the basics, not perfection,” he said, again, advice that is good for everyone.