Sleeping patterns affect aspects of metabolism that may impact obesity risk; our lab is interested in studying whether sleep patterns play a role in the development of obesity. Individuals with late bedtimes and late rise times tend to have greater food intake which includes more fast food and sugar-sweetened beverages, less fruits and vegetables [1], larger portions, and later eating times [2] than those with earlier bedtimes. This sleeping pattern is highly prevalent: ~15 million Americans work on shifts other than regular day hours [3] and others subject themselves to 'social jetlag' (time difference between the middle of the sleep episode [midpoint of sleep] on work days and non-work days, similar to travel across time zones) [4]. The shift in sleep and meal times associated with these lifestyles results in misalignment of sleep and eating behaviors with the circadian clocks. These clocks, located in the brain and organs throughout the body, regulate metabolism and behavior and are affected by sleep and feeding. Disruption of clock genes in individual organs may be in part responsible for metabolic dysregulation [5]. Altering the coordination of sleep and meal timing may affect food reward valuation (brain) and metabolism (peripheral organs) to promote obesity and IR, observed more frequently in shift workers. This is the focus of this randomized, crossover, controlled study of 4 phases: