Abstract
Introduction
Insufficient sleep impairs insulin sensitivity; however, the mechanism(s) by which this occurs are unknown. We previously reported an elevation in plasma free fatty acid concentration during insufficient sleep, suggesting dysregulated lipid metabolism. Lipid accumulation in muscle—specifically certain species of diacylglycerol (DAG)—is associated with impaired insulin sensitivity. We therefore tested the hypothesis that insufficient sleep leads to skeletal muscle DAG accumulation.
Methods
As part of an ongoing study, thirteen sedentary, healthy, lean adults (25.8±3.2y; 22.7±1.9kg/m2; 3F; mean±SD) participated in a controlled 6-day in-laboratory protocol with 9h in bed (habitual sleep) followed by 4 nights of 5h in bed (insufficient sleep), achieved by delaying bedtime by 4 hours. For one week prior to the study, participants maintained a 9h sleep schedule. Participants consumed energy balanced diets 3 days prior to and throughout the laboratory protocol. Insulin sensitivity was assessed using a hyperinsulinemic euglycemic clamp before and after insufficient sleep. Skeletal muscle biopsies of the vastus lateralis were taken immediately before each clamp. In a subset of subjects (n=10), quantitative lipidomic analyses using LC/MS/MS were performed on biopsied muscle tissue.
Results
Insulin sensitivity was impaired following insufficient sleep (10.7±1.5 vs 9.6±1.2 mg/kg/min, p<0.05, mean±SEM). There were no changes in skeletal muscle concentration of total triglycerides (TAGs), nor specific TAG species. However, insufficient sleep tended to increase skeletal muscle accumulation of total 1,2-DAGs (p=0.13) and significantly increased specific saturated species of 1,2-DAG, including Di-C18:0 DAG (p<0.05), previously implicated in insulin resistance. In contrast, 1,3-DAGs are not thought to impair insulin sensitivity and specific species were decreased or unchanged during insufficient sleep.
Conclusion
Preliminary findings suggest that skeletal muscle lipid accumulation of diacylglycerol species during insufficient sleep may be a contributing mechanism by which insufficient sleep dysregulates metabolic physiology.
Support
NIH K01DK110138, R03 DK118309, UL1 TR002535, and GCRC RR-00036