Abstract P171: Does Sleep Loss Affect Sympatho-excitatory Reactivity Of Blood Pressure In The Morning In People With Untreated Hypertension? A Preliminary Analysis.

Abstract

Objective: To determine the effect of sleep on the morning sympatho-excitatory reactivity of blood pressure (BP) in patients with untreated hypertension while controlling for the effects of the circadian system. Methods: Four participants (aged 50-63 y) underwent a randomized cross-over trial consisting of an 8-h overnight sleep opportunity and a night of 8-h supine rested wakefulness in dim light. After each trial, we measured beat-to-beat BP and heart rate (HR) at rest and during 2 min of the sympatho-excitatory stress, isometric handgrip exercise (IHG at 30% of maximal voluntary contraction), followed by 2 min of post-exercise ischemia (PEI). Sympathetic vasomotor modulation was analyzed at rest by the low-frequency band of systolic BP variability (LF SBP , mmHg 2 ). The effect size (ES) for repeated measures (Cohen’s d rm ) was used to compare absolute values at rest and the change in HR and mean BP during IHG and PEI as not meaningful (<0.2), small (0.2-0.49), moderate (0.50-0.79), or large (≥0.80). Results: After wakefulness, resting mean BP and sympathetic vasomotor modulation were both higher than after sleep with large ES (151±21 vs. 137±17 mmHg: ES=0.9, 95%CI [+1.3, +0.4]) and (12±9 vs. 6±2 mmHg 2 ; ES=0.9 95%CI [+1.7, +0.1]), respectively. BP reactivity was higher after wakefulness than after sleep with large ES at IHG min 2 and PEI min 1 and moderate ES at PEI min 2 (Figure 1), while HR was higher only at IHG min 2 with large ES. Conclusion: Our data suggest that sleep loss increases sympathetic vasomotor modulation and sympatho-excitatory reactivity of BP to morning physical stress in patients with untreated hypertension increasing their risk for adverse cardiovascular events.