Sleep Duration and Cardiovascular Health

PRIMARY OBJECTIVES: 1\. To test the hypothesis that vascular endothelial function in the brachial artery, and other associated cardiovascular risk markers are impaired in short sleepers and long sleepers as compared to the control group of average duration sleepers. To test the hypothesis that the optional intervention to maintain an 8-hour per night sleep schedule will alleviate vascular endothelial function impairment. OUTLINE: Participants will measure sleep, physical activity, and blood pressure with at-home devices before coming in for one in-lab visit, where they will have vascular function and blood markers measured, as well as an optional CT scan to measure calcium in the coronary arteries. An optional intervention may occur after this: Participants will continue the at-home measures while maintaining a chosen regular 8-hour per night sleep schedule, before coming in for a second in-lab visit with all same measures except for CT scan.