Context: Epidemiologic data indicate that reduced sleep duration is associated with increased incidence of type-2 diabetes.

Objective: To test the hypothesis that, when part of a Western-like lifestyle, recurrent bedtime restriction may result in decreased glucose tolerance and reduced insulin secretion and action.

Design: Randomized crossover study.

Setting: University clinical research center and sleep research laboratory

Participants: 11 healthy volunteers (5F/6M) with a mean (±SD) age of 39±5 y and BMI 26.5±1.5 kg/m2.

Intervention: Two 14-day periods of controlled exposure to sedentary living with ad libitum food intake and 5.5- or 8.5-hour bedtimes.

Main Outcome Measures: Oral and intravenous glucose challenges were used to obtain measures of glucose tolerance, glucose effectiveness, insulin secretion, and insulin sensitivity at the end of each intervention. Secondary measures included circulating concentrations of the glucose counter-regulatory hormones, cortisol, growth hormone, epinephrine, and norepinephrine.

Results: Bedtime restriction reduced daily sleep by 122±25 min. Both study periods were associated with comparable weight gain, however, recurrent sleep restriction resulted in reduced oral glucose tolerance (2-h glucose value 144±25 vs. 132±36 mg/dL; P<0.01) and insulin sensitivity (S_I 3.3±1.1 vs. 4.0±1.6 (mU/L)^-1.min^-1; P<0.03), and increased glucose effectiveness (S_G 0.023±0.005 vs. 0.020±0.005 min^-1; P<0.04). While 24-hour cortisol and growth hormone concentrations did not change, there was a modest increase in 24-hour epinephrine and nighttime norepinephrine levels during the 5.5-hour bedtime condition.

Conclusions: Experimental bedtime restriction, designed to approximate the short sleep times experienced by many individuals in Westernized societies, may facilitate the development of insulin resistance and reduced glucose tolerance.