THE EFFECT OF SLEEP CHARACTERISTICS ON THE ARTERIAL STIFFENING RESPONSE FROM ACUTE BOUTS OF SITTING
Elizabeth Moody, Alexander Pomeroy, Kristin Ondrak, Erik D Hanson FACSM
University of North Carolina at Chapel Hill, NC, USA
BACKGROUND: Approximately 33% of U.S. adults experience poor sleep, which is linked to elevated arterial stiffness (AS), an indicator of cardiovascular disease risk. Poor sleep may modify the AS response to prolonged sitting, which is known to acutely increase carotid-femoral pulse wave velocity (cfPWV), the gold standard for AS measurement. Movement breaks have been shown to reduce this effect. This study aims to determine 1) which measures of poor sleep impact baseline pulse wave velocity (PWV), and 2) whether these characteristics affect AS response to uninterrupted and interrupted prolonged sitting. We hypothesize that WASO and sleep latency will impact both baseline cfPWV and the change in cfPWV following sitting.
METHODS: The sample includes 21 men and women (30-60 y) who are sedentary (sitting ≥8 hr/day) and physically inactive (exercise <90 min/wk). Data was obtained from an R01 clinical trial (SWITCH). Each participant completed four 4-hour prolonged sitting conditions in a randomized order: (1) hourly five-min walking breaks; (2) hourly 15-min standing breaks; (3) alternating five-min walking and 15-min standing breaks, each once/hr; and (4) no breaks (control). Participants used a SleepScore Max to track their sleep metrics (WASO; sleep latency; REM sleep time) two nights prior to each visit. The primary outcome, cfPWV, was measured with a Vicorder (SMT Medical) device before and after each condition. For Aim 1, linear regression assessed the contributions of sleep variables to PWV. For Aim 2, linear mixed models examined the relationship between sleep characteristics and the change in cfPWV.
RESULTS: For Aim 1, a significant positive correlation was found between WASO and baseline cfPWV (p = 0.021, R2 = 0.0756) with an estimated increase of 0.0081 m/s per 1 minute increase of WASO when variables were analyzed independently. For Aim 2, REM sleep time was a significant positive predictor of cfPWV change (p = 0.031, R2 = 0.3635) with an estimated 0.00835 m/s increase in cfPWV change per 1 minute increase in REM time when condition was removed as an effect. These findings highlight the potential importance of WASO and REM sleep in modulating AS and its response to prolonged sitting and support further research of sleep as a factor for cardiovascular risk.Bachelor of Art
