Stable Sleep Pattern Before Sleep Loss

Purpose and hypothesis The aim of this study will be to test the hypothesis that stable sleep, as defined by a consistent (low variability) bedtime and wake-time schedule, will diminish the negative effect of sleep deprivation on vascular function. Study design and procedures Thirty adults (15 men, 15 women) will complete a 6-week study that will involve five study visits. The first visit will include informed consent, collection of demographic data, sleep- and health-related surveys, and familiarization with study procedures. Participants will then be block randomized to either habitual sleep followed by stable sleep, or stable sleep followed by habitual sleep - each sleep condition will lasts two weeks. In the habitual sleep condition, participants will be asked to follow their normal routine without concern about their sleep duration. In the stable sleep condition, participants will be asked to keep the same bedtime and wake-time schedule without deviation. Bedtime and wake-times will be determined by the researchers, but individualized for each participant so that their usual sleep duration (based on self-report) is met. Sleep will be monitored throughout the study using research-grade motion sensors worn at the wrist. Resting blood pressure, blood vessel vasodilatory function, and cardiovascular responses to exercise will be our main outcome variables. These variables will be measured before (on day #13) and after (on day #14) one night of sleep deprivation. Total sleep deprivation is a well-established experimental model to understand the acute effects of insufficient sleep on vascular function in humans.