People with body clocks set to late tend to get more diabetes, even after you account for their terrible lifestyle choices.
“Early to bed and early to rise makes a …”
How does the rest of that go?
Did you answer “man healthy, wealthy and wise” or “man or woman miss out on the night life”?
The Back Page will hazard that as upstanding, hard-working medical types you inclined towards the former.
It can feel as though the world has it in for you if you are an evening-chronotype type. Being up with the larks is associated with a wholesome character, clean living and a good work ethic, while staying and getting up late is seen as lazy, ill-disciplined and disreputable.
The Back Page would love to announce that science has come to our rescue, but unfortunately there’s nothing in this study in the Annals of Internal Medicine to repair the seedy reputation of us night-adjusted folks.
Previous work by the same team discovered that people with more irregular sleep schedules were more prone to diabetes and cardiovascular disease, and were more likely to have evening chronotypes.
In this study the authors took data on around 63,700 nurses from the Nurses Health Study II and looked at the relationship between chronotype and diabetes incidence, then adjusted it for diet quality, physical activity, alcohol intake, BMI, smoking and sleep duration. Chronotype, aka circadian preference, was measured by something called the Morningness-Eveningness Questionnaire and subjects were divided into “definite evening”, “definite morning” and intermediate groups.
The definite evening folks were 72% more likely to acquire diabetes over the decade of followup than the definite mornings, and the intermediates were 21% more likely, after adjusting for sociodemographic factors, shift work, and family history of diabetes.
Lifestyle factors accounted for a big chunk of this correlation, but not all of it. After adjusting further for diet, alcohol etc, as well as the other variables, the difference between evening and morning shrank to 19%.
Interestingly the diabetes link disappeared for eveningers who worked the night shift but persisted in those who worked day shift, defying their chronotype.
Those with evening chronotypes were – you guessed it – more likely to drink alcohol in higher quantities, have a poor diet, get less sleep, smoke, and have unhealthy weight, BMI and physical activity.
Co-author Tianyi Huang, an assistant professor of Medicine at Brigham and Women’s Hospital and Harvard Medical School, said because chronotype was partly genetically determined it might be hard to change.
“People who think they are ‘night owls’ may need to pay more attention to their lifestyle because their evening chronotype may add increased risk for type 2 diabetes,” he said.
“When chronotype was not matched with work hours we saw an increase in type 2 diabetes risk. That was another very interesting finding suggesting that more personalised work scheduling could be beneficial.”
Your scribe spent some years working late afternoon-evening shifts, and has never felt better rested. But even without the social disruption, missing out on morning and evening hours when the light is magical was a privation all on its own, which is why we’ll keep struggling out of bed at sparrow’s for the foreseeable.
Sending story tips to penny@medicalrepublic.com.au is a wholesome lifestyle choice.
