24-HR AMBULATORY BLOOD PRESSURE MONITORING & ACTIGRAPHY-MEASURED SLEEP DISTURBANCES

Abstract

Objective: Non-dippers tend to have a high risk for cardiovascular disease. Actigraphy has been validated for objective measures of sleep in clinical-based and population-based studies. PURPOSE: The purpose of this study was to assess Actigraphy measured sleep disturbances among dippers and non-dippers. Design and method: Thirteen (6F/7 M) relatively healthy and clinically free of any sleep-related disorder were recruited. 24-hr Ambulatory blood pressure (BP) monitor applied to the non-dominant arm was used to profile dipping and nondipping status (awake value - sleep value)/awake value < 0.1. 24-hr wrist (dominant arm) Actigraphy data were collected in 1 min epochs, and the ‘Cole-Kripke’ sleep algorithm for adults was used to assess sleep. Sleep disturbance metrics including sleep efficiency, total min in bed, total sleep time, number of awakenings, long wake after sleep onset (WASO: number of min awake between sleep onset and time of final waking) were assessed. Results: Awake SBP (Mean ± SD) for non-dippers (N = 7) 120.2 ± 8.1 vs. dippers 129.1 ± 8.1mmHg; sleep SBP for non-dippers 117.2 ± 8.4 vs. dippers 114.3 ± 5.5mmHg. Non-dippers vs. dippers sleep efficiency (85 vs. 89%); total min in bed (408 vs. 450 min); total sleep time (352 vs. 398 min); number of awakenings (21.1 ± 10.2 vs. 21.1 ± 3.1) were not statistically different. WASO for non-dippers 55.5 ± 32.5 vs. dippers 49.5 ± 18.2 min (p < 0.05). Conclusions: In our preliminary study with a very small N, WASO was 10% higher in non-dippers compared to dippers despite having similar number of awakenings. This indicates that participants with a non-dipper blood pressure profile have disturbed sleep with being awake for a greater amount of time between sleep onset and time of final waking when compared to dippers. Thus, sleep assessment among non-dippers might be reasonable.