Sleep quality and blood pressure dipping in normal adults

To investigate the relationship between sleep quality and nocturnal blood pressure dipping in normal subjects. We hypothesized that sleep quality correlates with dipping. Cross-sectional study. Unattended polysomnography in the home followed by a 24-hour ambulatory blood pressure measurement. Eighty-eight self-described normal subjects were evaluated; 26 were excluded due to an apnea-hypopnea index > or = 10. None were taking antihypertensive medications. N/A. Subjects were divided into dippers and nondippers based on > or = 10% drop in nocturnal mean arterial pressure (MAP). Sleep-quality variables included total sleep time; sleep latency; percentage of stages 1, 2, 3, 4, and rapid-eye-movement sleep; percentage of wake time after sleep onset (WASO); total arousal index; and sleep efficiency. Of the remaining 62 subjects, 17.7% were nondippers, and 7 were hypertensive. There was no difference in age, body mass index, apnea-hypopnea index, blood pressure, or sleep quality between groups. Stage 4 sleep correlated significantly with dipping of diastolic blood pressure and MAP (r = 0.410 and 0.378, respectively, P < or = .002), and percentage of WASO was negatively correlated with dipping of diastolic blood pressure (r = -0.360, P = .004), suggesting that greater dipping was associated with better sleep quality. On multivariate analyses, Stage 4 sleep was independently associated with dipping of diastolic blood pressure (P = .034) after adjusting for screening MAP, percentage of WASO, total arousal index, and Stage 1 sleep. The same link was found between Stage 4 sleep and dipping of MAP (P = .05) after adjusting for screening MAP, age, sex, and body mass index. Repeat analyses excluding hypertensives yielded similar findings. Our data suggest that deeper and less-fragmented sleep is associated with more blood pressure dipping in normal subjects.