We all know that some people rise before dawn, and some folks stay up with the late-night TV hosts. People often identify as morning birds or night owls. Usually, we shrug it off as our natural rhythm and build our schedules around it without thinking much about it. But, a new study has found that night owls might need to think harder about their habits. According to data from 63,676 female nurses, night owls are 19 percent more likely to have a blood sugar concern.
“Chronotype, or circadian preference, refers to a person’s preferred timing of sleep and waking and is partly genetically determined, so it may be difficult to change,” said corresponding author Dr. Tianyi, an associate epidemiologist at Brigham and Women’s Hospital.
Her group previously found that people with irregular sleep schedules had a higher risk for heart disease and blood sugar concerns. Being a night owl or having an “evening chronotype” makes you more likely to have irregular sleep patterns. This study examined the links between chronotype, lifestyle factors and blood sugar concern risks.
The data in the study was self-reported. It was collected between 2009 and 2017. Nurses told them their chronotype, diet quality, weight, BMI, sleep schedule, smoking, alcohol and exercise habits and family history of blood sugar concerns. They also self-reported their own blood sugar concerns.
Women in the study broke down into three chronotypes. About 11 percent were “definite evening” people, around 35 percent were “definite morning” people and the rest were somewhere neither one nor the other. The researchers found that night owls had a 72 percent higher risk of blood sugar concerns. However, the risk dropped significantly after adjusting for irregular sleep and other lifestyle factors. But, even after the decrease, night owls were 19 percent more likely to have blood sugar concerns.
People with an evening chronotype were likelier to drink high amounts of alcohol, smoke, eat poorly, not sleep enough, be overweight and have poor exercise habits. All of those attributes are risk factors for blood sugar concerns. Considering that, the 72 percent higher risk might not be surprising. However, when the researchers stripped out all of those factors and found the night owls who didn’t drink or smoke, had a healthy exercise, diet and sleep routine and maintained a normal body weight, they still had the 19 percent higher risk.
When the researchers looked at who had the healthiest lifestyles, only six percent were night owls. Unfortunately, 25 percent of people with the least healthy lifestyles were evening chronotypes. When tired, you make poorer food choices and are less motivated to exercise. It can make sticking to a healthy plan harder.
There is a genetic component to whether you’re an early bird or a night owl. The researchers want to look at that to see if genes explain the 19 percent risk that can’t be attributed to lifestyle factors.
The study found that nurses who were night owls but worked the day shift were more likely to have blood sugar concerns than night shift workers. That means that finding the right scheduling could be helpful. So many people push themselves into early bedtimes because it’s the “normal” thing to do. But, maybe if night owls sleep on their schedule and get regular, uninterrupted sleep, their risk would decrease.
“If we are able to determine a causal link between chronotype and [blood sugar concerns] or other diseases, physicians could better tailor prevention strategies for their patients,” said Dr. Sina Kianersi, a postdoctoral research fellow.
Finding individualized strategies is the best step forward. Everyone’s needs are different, and once doctors know how blood sugar concerns and chronotypes are linked, they can help people make the right plan for them.