Effects of Acute Sleep Reduction and Aerobic Exercise on Metabolic Function in Healthy Adults

INTRODUCTION: The number of adults who receive insufficient sleep is progressively increasing, impacting the established relationship between sleep and metabolic function. PURPOSE: The purpose of this study was to explore the effects of acute sleep reduction on metabolic variables at rest and during aerobic exercise. METHODS: Healthy, active adults (n=11; 26.4±5.4 yr; 45% female) were screened to ensure eligibility (i.e., meeting the CDC’s sleep recommendations of 7-9hr/night, apparently healthy, recreationally active, and non-smoking), characterize body composition via DXA and measure maximal cardiovascular capacity (VO2max). Utilizing a within subjects, repeated measures design, participants completed an initial 7d period of habitual sleep (CON) followed by a 7d period of sleep reduction (SR; sleeping ~3hr less per night). Sleep habits were evaluated throughout via accelerometry (Actigraph wGT3X-BT) and sleep diary. Immediately after CON and SR, participants reported to the laboratory after an overnight fast for venipuncture blood draw and fingerstick assessment of glucose and lactate. Next, seated resting carbohydrate (CHO) and fat oxidation were measured via indirect calorimetry (PARVO Medicis). After resting measures, participants completed a 45min aerobic exercise (AE) challenge on a cycle ergometer at a workload corresponding to 70% of their VO2max. During the AE challenge, RPE, lactate, and gas exchange was monitored in regular intervals. A 30-min post AE blood draw was completed to assess IL6. CHO and fat oxidation rates were calculated via the Frayn method and IL6 quantified via ELISA. RESULTS: Sleep was reduced by 31% (p≤0.05) during SR (CON: 8.1±0.3; SR: 5.4±0.2 hr/night). Sleep efficiency (5%) increased, while average number of awakenings (42%) and sleep fragmentation index (24%) decreased during SR (p≤0.05). SR increased (p≤0.05) resting CHO oxidation (45%), Kcals from CHO (45%) and total Kcal (23%). Resting glucose and IL6 levels remained unchanged after SR (p>0.05). IL6 levels increased (p≤0.05) following AE in CON (161±68%) and SR (133±37%) similarly. While the lactate response remained unchanged following SR (p>0.05), average RPE during exercise increased 3% after SR (p≤0.05). CONCLUSION: Overall, acute sleep reduction increased reliance on CHO metabolism at rest.