Effects of sleep restriction on glucose control and insulin secretion during diet-induced weight loss

Insufficient sleep is associated with changes in glucose tolerance, insulin secretion, and insulin action. Despite widespread use of weight-loss diets for metabolic risk reduction, the effects of insufficient sleep on glucose regulation in overweight dieters are not known. To examine the consequences of recurrent sleep restriction on 24-hour blood glucose control during diet-induced weight loss, 10 overweight and obese adults (3F/7M; mean [SD] age 41 [5] y; BMI 27.4 [2.0] kg/m(2)) completed two 14-day treatments with hypocaloric diet and 8.5 or 5.5-h nighttime sleep opportunity in random order 7 [3] months apart. Oral and intravenous glucose tolerance test (IVGTT) data, fasting lipids and free-fatty acids (FFA), and 24-hour blood glucose, insulin, C-peptide, and counter-regulatory hormone measurements were collected after each treatment. Participants had comparable weight loss (1.0 [0.3] BMI units) during each treatment. Bedtime restriction reduced sleep by 131 [30] min/day. Recurrent sleep curtailment decreased 24-hour serum insulin concentrations (i.e. enhanced 24-hour insulin economy) without changes in oral glucose tolerance and 24-hour glucose control. This was accompanied by a decline in fasting blood glucose, increased fasting FFA which suppressed normally following glucose ingestion, and lower total and LDL cholesterol concentrations. Sleep-loss-related changes in counter-regulatory hormone secretion during the IVGTT limited the utility of the test in this study. In conclusion, sleep restriction enhanced 24-hour insulin economy without compromising glucose homeostasis in overweight individuals placed on a balanced hypocaloric diet. The changes in fasting blood glucose, insulin, lipid and FFA concentrations in sleep-restricted dieters resembled the pattern of human metabolic adaptation to reduced carbohydrate availability.