Sleep Restriction and Postprandial Lipemia

Sleep restriction increases overnight and early morning non-esterified fatty acids (NEFA) levels, which are correlated with whole-body decreases in insulin sensitivity, consistent with the observed impairment of intracellular insulin signaling. Adipose tissue biopsies from sleep restricted subjects that are insulin stimulated have reduced phosphorylation of protein kinase B (pAKT). This protein is involved in suppression of intracellular lipolysis and NEFA release. Aerobic exercise has beneficial effects on postprandial lipemia and insulinemia in normal-weight and obese individuals. Acute moderate-intensity aerobic exercise (30-90 min) performed 12-18 h before an oral fat tolerance test or mixed meal test reduces postprandial triglycerides (TG) and insulin concentrations. This response is largely dependent upon the exercise-induced energy deficit as the response is abolished when the calories expended during exercise are replaced. However, it is not known if sleep restriction will interfere with the beneficial effects of prior exercise on postprandial lipemia. The aim of this project is to investigate if sleep restriction negates the positive effect that exercise has on postprandial lipemia. It is hypothesized that sleep restriction will negate the beneficial effects of prior exercise on postprandial lipemia. Additionally sleep restriction will result in a worsening of the lipid profile compared to no exercise. For the proposed study, the investigators will use a repeated measures analysis of variance (ANOVA) (4 study conditions (no exercise+ sleep restriction, no exercise+normal sleep, exercise+normal sleep, exercise+sleep restriction) x time will be used to analyze changes in NEFA and TG concentrations while a one way ANOVA will be used to analyze area under the curve of the NEFA and TG concentrations.