Effects of Sleep Duration and Architecture on Insulin Sensitivity

This pilot clinical trial will test the hypotheses that sleep restriction (for 5 nights), in comparison to "normal sleep", will: 1. Decrease peripheral insulin sensitivity and glucose tolerance, as measured by the hyperinsulinemic-euglycemic clamp and oral glucose tolerance test. 2. Decrease hepatic insulin sensitivity, as assessed by stable isotope studies of endogenous glucose production, gluconeogenesis and glycogenolysis.