Glucose Tolerance after different Sleep Regimes: Effects of Sleep Deprivation, Sleep Restriction, and Recovery

Abstract

Introduction: Shift-work is related to metabolic and cardiovascular disease. Sleep restriction and circadian misalignment have been shown to decrease glucose tolerance. Since shift-work is often associated with a combination of sleep restriction, total sleep deprivation and intermittent recovery sleep we tested (i) whether acute sleep deprivation and repeated sleep restriction exhibit similar effects on glucose tolerance, (ii) whether one night of recovery sleep after repeated sleep restriction is sufficient to restore glucose tolerance, and (iii) whether the effects of acute sleep deprivation and prior sleep restriction are cumulative. Methods: Morning oral glucose tolerance (OGTT: 75g dextrose/300ml water; >10h fasting) was tested during a 12-day inpatient study in an intervention group (IG) (N=18; 9 females, mean age 26±3 years, BMI 23.2±2.0) and a control group (CG) (N=9; 3 females, mean age 25±5 years, BMI 23.5±3.4). In the IG OGTTs were run after (i) two nights of baseline sleep (8h TIB), (ii) five nights of sleep restriction (5h TIB), (iii) one night of recovery (8h TIB), and (iv) 24h of sustained wakefulness following recovery. In the CG OGTTs were taken at the same time points except that TIB was 8h for all sleep episodes. Blood samples were taken immediately prior to the OGTT and every 30min thereafter for 120min. Mixed ANOVAs with Tukey adjustment compared glucose levels in each group between interventions. Results: Glucose tolerance decreased after five nights of sleep restriction: compared to baseline, blood glucose stayed elevated 60min (Δ19.1±6.2 mg/dl (SE), p<0.02), 90min (Δ25.6±6.0 mg/dl, p=0.0005), and 120min (Δ24.8±5.1 mg/dl, p<0.0001) after intake. Glucose levels were still increased after recovery (90min: Δ22.6±6.0 mg/dl, p=0.002; 120min: Δ16.2±5.1 mg/dl, p<0.02), but were not different from baseline after 24h of wakefulness. Sleep deprivation in the CG did not alter glucose tolerance. Conclusion: Restricting the sleep time to 5h for five nights decreased glucose tolerance. One 8h recovery sleep episode did not restore glucose tolerance. One night of sleep deprivation did not affect glucose tolerance and did not add to the effects of prior sleep restriction. A different metabolic regulation during the wake state might have prevented glucose tolerance from decreasing.