Blood pressure dipping and sleep quality in the Wisconsin Sleep Cohort

Aims: Nondipping blood pressure (BP) is associated with higher risk for hypertension and advanced target organ damage. Insomnia is the most common sleep complaint in the general population. We sought to investigate the association between sleep quality and insomnia and BP nondipping cross-sectionally and longitudinally in a large, community-based sample. Methods: A subset of the Wisconsin Sleep Cohort (n = 502 for cross-sectional analysis and n = 260 for longitudinal analysis) were enrolled in the analysis. Polysomnography measures were used to evaluate sleep quality. Insomnia symptoms were obtained by questionnaire. BP was measured by 24-h ambulatory BP monitoring. Logistic regression models estimated cross-sectional associations of sleep quality and insomnia with BP nondipping. Poisson regression models estimated longitudinal associations between sleep quality and incident nondipping over a mean 7.4 years of follow-up. Systolic and diastolic nondipping were examined separately. Results: In cross-sectional analyses, difficulty falling asleep, longer waking after sleep onset, shorter and longer total sleep time, lower sleep efficiency and lower rapid eye movement stage sleep were associated with higher risk of SBP and DBP nondipping. In longitudinal analyses, the adjusted relative risks (95% confidence interval) of incident systolic nondipping were 2.1 (1.3-3.5) for 1-h longer waking after sleep onset, 2.1 (1.1-5.1) for 7-8 h total sleep time, and 3.7 (1.3-10.7) for at least 8-h total sleep time (compared with total sleep time 6-7 h), and 1.9 (1.1-3.4) for sleep efficiency less than 0.8, respectively. Conclusion: Clinical features of insomnia and poor sleep quality are associated with nondipping BP. Our findings suggested nondipping might be one possible mechanism by which poor sleep quality was associated with worse cardiovascular outcomes.