Objective sleep quality and night-time blood pressure in the general elderly population: a cross-sectional study of the HEIJO-KYO cohort.

Objectives: Night-time blood pressure (BP) - prognostically more important than circadian BP variability - has not been evaluated for quantitative associations with objective sleep quality in large populations.

Methods: The cross-sectional study measured actigraphic sleep parameters and night-time BP for two nights in 1101 elderly participants.

Results: Mean age of the participants was 71.8 years, and mean night-time SBP and DBP were 115.9 ± 16.2 and 66.9 ± 8.4 mmHg, respectively. Multivariable analysis controlling for potential confounders revealed that the lowest sleep efficiency quartile group exhibited significantly higher night-time SBP and DBP than the highest quartile group [mean difference: SBP, 4.7 mmHg, 95% confidence interval (CI), 2.0-7.3; DBP, 2.3 mmHg, 95% CI 0.9-3.7]. The longest wake after sleep onset and sleep-onset latency quartile groups exhibited significantly higher night-time SBP (3.1 mmHg, 95% CI 0.3-5.9 and 3.4 mmHg, 95% CI 0.8-6.0) and DBP (2.0 mmHg, 95% CI 0.5-3.5 and 1.9 mmHg 95% CI 0.5-3.3), respectively, than the shortest quartile group. Significantly lower night-time SBP (3.0 mmHg, 95% CI 0.01-6.1) was observed in the longest total sleep time quartile group than in the shortest quartile group. These results were similar on sensitivity analyses excluding participants with possible sleep-disordered breathing (n = 69) or nocturnal hypertension (n = 503).

Conclusion: Decreased sleep quality on actigraphy was significantly associated with higher night-time BP in a large general elderly population. Clinically significant increase in night-time BP exists in relation to decreased objective sleep quality.