A study has found that women with sleeping difficulties are at increased risk for developing type 2 diabetes. The study followed thousands of women and found a significant association between sleeping difficulty and later type 2 diabetes during up to 10 years of follow-up.
Scientists used data from more than 133,000 women who were enrolled in the Nurses' Health Study and the Nurses' Health Study II, which are both ongoing long-term prospective studies of women who were generally healthy when they enrolled. Participants answer questionnaires about their health regularly. Data was collected between 2000 and 2010 in the NHS and between 2001 and 2011 in the NHSII.
During the 10 years of follow-up, the researchers found 6,407 cases of type 2 diabetes.
The researchers looked at four types of sleep problems, all of which were self-reported by the participants: difficulty falling or staying asleep, frequent snoring, getting less than 6 hours sleep, and either sleep apnea or rotating shift work.
Self-reported sleeping difficulties were associated with higher body mass index (BMI), with less physical activity, and higher rates or hypertension and depression. When the researchers adjusted for these and other health and behavioral characteristics, sleeping difficulty was still associated with a 22% increase in the risk for type 2 diabetes.
Women with two of the four sleep difficulties studied had double the risk of developing type 2 diabetes as those with none. Women with all four had almost four times the risk of developing type 2 diabetes.
According to the lead author of the study, Dr. Frank B. Hu, a professor of nutrition and epidemiology at Harvard, sleep problems are associated with excess production of the hormones ghrelin (which increases appetite) and cortisol (which increases stress and insulin resistance). Both ghrelin and cortisol are linked to problems with metabolism that increase the risk for diabetes. It is not just a matter of the amount of sleep that is associated with an increased risk of diabetes, but also of the quality of sleep, Dr. Hu told The New York Times.
The study was published in the journal Diabetologia.