Relationship between base blood pressure during sleep and health-related quality of life in healthy adults.

There are many reports indicating that night time blood pressure (BP) is closely associated with target organ damage. However, BP in the waking period is influenced by physical activity and also by the psychological status. Recently, base BP (BP0: minimum and stable BP during sleep) has been reported to correlate with organ damage in hypertensives. However, little is known about the implications of BP0. We examined how BP0 is associated with BP, heart rate variability and health-related quality of life (HRQOL) in healthy subjects. One hundred and thirty-five participants, composed of 88 male and 47 female (age: 21-33 years) underwent a 24-h ambulatory BP monitoring (ABPM). Sympathetic nervous activity (ratio of low-frequency to high-frequency component: LF/HF) and parasympathetic nervous activity (high-frequency component: HF) were calculated by electrocardiogram monitoring. BP0 was calculated as previously reported. HRQOL was assessed by Medical Outcome Study Short-Forum 36-Item Health Survey. Base systolic BP (SBP0) positively correlated with 24-h systolic BP (SBP) (r=0.662, P<0.0001) and night time SBP (r=0.810, P<0.0001). SBP0 positively correlated with 24-h LF/HF (r=0.214, P<0.02) and night time LF/HF (r=0.326, P<0.001). Moreover, SBP0 negatively correlated with the scores of body pain (r=-0.223, P<0.02). Multiple linear regression analysis showed that SBP0 correlated with gender (P<0.01), night time LF/HF (P<0.04) and the scores of body pain (P<0.04). In conclusion, SBP0 correlated with BP, LF/HF and the scores of body pain (HRQOL). SBP0 may be a useful indicator for assessing 24-h BP, sympathetic nervous functions and HRQOL in healthy subjects.