A new study finds that “night owls” are more likely than “early birds” to have unhealthy lifestyle behaviors and an increased risk of developing Type 2 diabetes.
Being a night owl isn’t about staying up late to party. It’s about a person’s circadian preference, or having a natural body clock that is partly genetically set to stay up late. That means night owls are wired differently from people who seem to automatically wake up at the crack of dawn and nod off at an early hour.
An analysis of data from more than 60,000 female nurses participating in the Nurses’ Health Study II revealed that night owls were more likely to consume unhealthy diets, to exercise less, to have a higher body mass index, to sleep fewer hours and to smoke cigarettes than the early birds, according to the report published in the Annals of Internal Medicine.
Night owls were more likely to develop diabetes — about 19% after the researchers accounted for the impact of unhealthy habits associated with being a night owl. And that means there may be something about wake and rise times being shifted later that raises the risk of diabetes.
“A 19% increased risk, after adjusting for other factors, is a strong risk factor,” said the study’s senior author, Tianyi Huang, an assistant professor of medicine at the Harvard Medical School and an associate epidemiologist at the Brigham and Women’s Hospital in Boston. Among the women in the study, 11% reported they were night owls, while 35% said they were early birds. The rest, around half, didn’t identify strongly as either a morning or evening person.
The new research is the latest evidence to show that being a so-called evening chronotype — or feeling more energetic at night — can be hazardous to your health. Previous research has linked being a night owl to obesity and heart disease. Huang suspects the risk linked simply to being a night owl is due to a person’s chronotype being out of sync with their environment, in particular, their work schedule. “So, many night owls go to bed late but have to get up early in the day to work,” he said. “In our study we found that among people with an evening chronotype who did night shift work there was no association with an increased risk of diabetes.”
Marie-Pierre St-Onge, director of the Center of Excellence for Sleep and Circadian Research at Columbia University Vagelos College of Physicians and Surgeons, said if it’s not possible to find jobs that can be done later in the day, then people with late-night body clocks need to be careful about their lifestyle habits. “If you are able to eat healthy, sleep well and be physically active, you’re at a lesser risk,” St-Onge said.
