Effects of Partial Sleep Deprivation on Cardiac Output During Cycling

The investigators recently published data showing systolic blood pressure is attenuated during cycling exercise in males but not females following acute partial sleep deprivation, compared to a night of normal sleep, despite no differences in power output. The mechanisms responsible for this sex difference remain unknown. The investigators have pilot data that suggests males have a reduction in cardiac output following acute partial sleep deprivation, but females do not. Therefore, the primary purpose of this study is to assess hemodynamics (blood pressure, stroke volume, and cardiac output) and plasma volume during cycling exercise following a night of normal sleep and partial sleep deprivation in otherwise healthy males and females.

Thirty young healthy adults (50% female) will be recruited to undergo three visits. The first visit will assess maximal oxygen uptake to determine aerobic fitness and metabolic exercise intensity zones. The following two testing visits will be randomized and will be completed after a night of normal sleep or acute partial sleep deprivation (early awakening, 40% normal sleep duration). Sleep will be measured 1-week before each visit subjectively (questionnaire) to determine habitual sleep timing and duration and objectively (wrist actigraphy) the night before each testing visit. Each testing visit will require participants to complete a constant load 60-minute bout of cycling. Before, during, and after the exercise protocol, the investigators will measure hemodynamics and plasma volume. Venous blood samples will be collected via intravenous lines.