After adjusting for lifestyle characteristics, researchers discovered that evening ‘chronotype,’ or staying up late and getting up late, was linked to a 19% higher risk of diabetes.
An key conclusion from a recent study is relevant for those who identify as night owls. Researchers from Brigham and Women’s Hospital, a founding institution of the Mass General Brigham healthcare system, discovered that those who slept later and woke up later had less healthy lives and were more likely to develop diabetes. The Annals of Internal Medicine publishes their findings.
Researchers have previously discovered that persons with evening chronotypes are more likely to have variable sleep patterns, and that those with more erratic sleep habits are at an increased risk of diabetes and cardiovascular disease. In order to understand the connection between chronotype and diabetes risk in this study, lifestyle factors were also examined.
In addition to self-reported chronotype (the degree to which participants perceived themselves to be an evening person or a morning person), diet quality, weight, and body mass index, sleep timing, smoking behaviours, alcohol use, physical activity, and family history of diabetes, the team also examined data from 63,676 female nurses who participated in the Nurses’ Health Study II, which was collected from 2009 to 2017. The team used the subjects’ self-reports and medical records to assess whether they had diabetes.
The Nurses’ Health Study II, a collaboration between Harvard T.H. Chan School of Public Health and Brigham’s Channing Division of Network Medicine, is one of the most thorough studies to date exploring the risk factors for serious chronic diseases in women. Regular follow-up with study participants and periodic evaluations of lifestyle and health-related factors are two of the study’s advantages.
A ‘definite evening’ chronotype was reported by around 11% of participants, and a ‘definite morning’ chronotype was recorded by about 35%. Nearly half of the remaining population was classified as “intermediate,” which either meant they identified as neither morning nor evening people nor as being slightly more of one than the other.
Before taking into account lifestyle characteristics, the evening chronotype was linked to a 72 percent higher risk for diabetes. Evening chronotype was linked, when lifestyle factors were taken into account, to a 19% higher risk of diabetes. Only 6% of study participants who had the healthiest lifestyles had evening chronotypes. 25 percent of those who led the unhealthiest lifestyles were evening chronotypes.
Researchers discovered that people with evening chronotypes were more likely to consume more alcohol, consume poor-quality foods, have less sleep at night, smoke now, and have unhealthy weight, BMI, and physical activity levels.
Additionally, they discovered that nurses who worked day shifts rather than overnight shifts were the only ones who showed a relationship between the evening chronotype and diabetes risk.
The majority of the nurses in the Nurses’ Health Study are white women. Future research will be required to ascertain whether the trends found here are common across populations. The study’s findings indicate associations but do not establish causation. A person’s chronotype, predisposition for unhealthy behaviours, and risk of diabetes may be influenced by additional factors.
The next step is for the researchers to look into the genetic factors that determine chronotype and how they relate to diabetes and cardiovascular disease in larger, more diverse populations.