A preference for late-night activities may cause people to gain weight.
Prediabetes affects around 84 million people in the United States.
That is, 1 in 3 U.S. individuals are living with the condition, and 90 percent of them are not aware that they have it.
In prediabetes, blood sugar levels are higher than what is considered normal, but not high enough to warrant a diagnosis of type 2 diabetes.
Insufficient sleep or a disrupted sleep pattern are also known risk factors for obesity and diabetes. Previous research has suggested that being a "night owl," or having a preference for activities in the evening and going to bed late, raises the risk of being overweight, as well as having type 2 diabetes and dying prematurely.
So, researchers led by Dr. Sirimon Reutrakul, an associate professor of endocrinology, diabetes, and metabolism in the University of Illinois at Chicago College of Medicine, set out to examine whether being a night owl influenced body mass index (BMI) among people with prediabetes.
BMI is a measure of body fat in relation to a person's height and weight.
Thunyarat Anothaisintawee is the first author of the paper, which was published in the journal Frontiers in Endocrinology.
Sleep patterns, BMI, and prediabetes
Dr. Reutrakul and colleagues examined 2,133 people with prediabetes who were 64 years old, on average.
Using a questionnaire, the scientists assessed the participants' "eveningness" and "morningness" — that is, their preference for going to bed late and waking up early, respectively.
The scientists also assessed social jetlag, or the difference in sleep timing and duration between weekdays and weekends, in the participants.
Higher levels of social jetlag were found to correlate with a higher BMI. In people older than 60, eveningness was associated with a higher BMI as well. However, this effect was due to not having enough sleep, not to social jet lag.
"In patients with prediabetes," explain the study authors, "more evening preference was directly associated with higher BMI and indirectly through insufficient sleep duration."
"These data could inform further interventional studies to reduce BMI in this high-risk group," add Anothaisintawee and colleagues. Dr. Reutrakul also comments on the significance of the findings.
"Diabetes is such a widespread disease with such an impact on quality of life," she says, "that identifying new lifestyle factors that might play into its development can help us advise patients with an early stage of the disease on things they can do to turn it around and prevent prediabetes from becoming full-blown diabetes."
"Timing and duration of sleep are potentially modifiable [...] People can have more regular bedtimes and aim to have more sleep, which may help reduce BMI and the potential development of diabetes in this high-risk group."
Dr. Sirimon Reutrakul