Does sleep restriction attenuate the benefits of interrupting sitting on glucose metabolism? A pilot study

Purpose: Prolonged sitting and sleep restriction are both independent risk factors in the development of cardiometabolic disease. Interrupting sitting with short bouts of physical activity reduces cardiometabolic risk in rested individuals. However, 33‐45% of Australians are chronically sleep restricted. Given that prolonged sitting and sleep restriction influence the same cardiometabolic parameters, the aim of this pilot study was to determine whether the positive effects of interrupting sitting persist under the conditions of sleep restriction. Methods: This laboratory counterbalanced, crossover trial consisted of two 4 day (4 night) experimental conditions separated by a two‐week washout period. On the first night participants were given a 9‐h sleep opportunity to allow for steady state baseline measures the following day. Three consecutive nights of sleep restriction (5‐h sleep opportunity) followed. In the sitting condition (SIT), participants remained seated between 1000‐1800. In the physical activity condition (PA), participants completed 3‐min bouts of light‐intensity walking every 30 mins on a motorised treadmill. At all other times, in both conditions, participants remained seated, except when walking to the dining room or to use the bathroom (max 32 m). Six male participants were randomised to one of two trial orders, 1) SIT then PA, or 2) PA then SIT. Interstitial glucose concentrations were measured every 5 min using a continuous glucose monitor to derive average daily glucose concentrations. Analyses were conducted using a linear mixed‐effect ANOVA with condition (SIT or PA) and order (1 or 2) as fixed effects, and participant as a random effect. Results and Conclusion: Average daily glucose concentrations increased from baseline in both conditions after night one of sleep restriction (SIT = +1.13 mmolL−1; PA = +0.96 mmolL−1). No difference was observed between the SIT and PA condition across the three nights of sleep restriction (SIT = 5.7 ± 0.2 mmolL−1; PA = 5.6 ± 0.2 mmolL−1). These data support our contention that sleep restriction may attenuate the positive benefits of interrupting sitting time on glucose metabolism. Further research with larger samples appropriate control groups (8‐9 h sleep opportunities) should be conducted to confirm these findings.