A Prospective Study of Self-Reported Sleep Duration and Incident Diabetes in Women

A Prospective Study of Self-Reported Sleep Duration and Incident Diabetes in Women Najib T. Ayas , MD 1 2 , David P. White , MD 1 2 , Wael K. Al-Delaimy , MD, PHD 3 , JoAnn E. Manson , MD, DRPH 2 4 5 6 , Meir J. Stampfer , MD, DRPH 3 4 6 , Frank E. Speizer , MD 2 6 , Sanjay Patel , MD 1 2 and Frank B. Hu , MD, PHD 3 4 6 1 Division of Sleep Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston 2 Harvard Medical School, Boston 3 Department of Nutrition, Harvard School of Public Health, Boston 4 Department of Epidemiology, Harvard School of Public Health, Boston 5 Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston 6 Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts Abstract Short-term sleep restriction results in impaired glucose tolerance. To test whether habitually short sleep duration increases the risk of developing diabetes, we studied a cohort of 70,026 women enrolled in the Nurses Health Study, without diabetes at baseline, and who responded to a question about daily sleep duration in 1986. Subjects were followed until 1996 for the diagnosis of diabetes (1,969 cases). Long and short sleep durations were associated with an increased risk of diabetes diagnosis. The relative risks (RRs) for short (slept ≤5 h per day) and long (slept ≥9 h per day) sleepers were 1.57 (95% CI 1.28–1.92) and 1.47 (1.19–1.80), respectively. After adjustment for BMI and a variety of confounders, the RR was not significantly increased for short sleepers (1.18 [0.96–1.44]) but remained modestly increased for long sleepers (1.29 [1.05–1.59]). We then performed a similar analysis using only symptomatic cases ( n = 1,187). Adjusted RRs for symptomatic diabetes were modestly elevated in both short (1.34 [1.04–1.72]) and long (1.35 [1.04–1.75]) sleepers. Our data suggest that the association between a reduced self-reported sleep duration and diabetes diagnosis could be due to confounding by BMI, or sleep restriction may mediate its effects on diabetes through weight gain. Sleep restriction may be an independent risk factor for developing symptomatic diabetes. RR, relative risk Footnotes Address correspondence and reprint requests to Frank B. Hu, MD, PhD, Dept. of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115. E-mail: frank.hu{at}channing.harvard.edu . Received for publication 16 July 2002 and accepted in revised form 29 October 2002. A table