 On the first day of each study phase baseline, participants will come to the research center in the morning after an overnight,12 hour fast. Participants will have anthropometric measurements taken and will then be taken to the department of Radiology to undergo magnetic resonance imaging MRI scanning to assess body composition. Flow-mediated dilatation will be performed in the Cardiovascular Ultrasound Laboratory. They will then return to the the clinic for an oral glucose tolerance test. A blood sample will be taken for hormone measurements, and a sample of cells lining the blood vessel forearm vein will also be taken to assess endothelial function. Participants will begin the fixed bedtime routine that night. These baseline measurements will be repeated at endpoint, 6 weeks later. Body weight and waist circumference will be measured weekly and fasting blood samples will be taken at week 3 during adherence check visits. 