Psychological and Physical Stress-Induced Cardiovascular Reactivity and Diurnal Blood Pressure Variation in Women with Different Work Shifts.

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Abstract
There is increasing evidence that diurnal blood pressure (BP) variation, in addition to high BP per se, is related to target organ damage and the incidence of cardiovascular events. However, the determinants of diurnal BP variation are not adequately understood. This paper tests the hypothesis that cardiovascular reactivity to acute stress and/or delayed recovery predicts greater diurnal BP variation (i.e., a lower sleep/awake BP ratio). We studied the relationship of diurnal BP variation (assessed by ambulatory BP monitoring) to mental stress (mental arithmetic and anger recall tasks) and physical stress (treadmill)-induced cardiovascular reactivity and recovery in 87 female nurses who worked different shifts. The sleep/awake systolic BP (SBP) ratio was negatively correlated with relative SBP reactivity (maximum SBP increase/baseline SBP: r =-0.21, p =0.06) and relative stress response (average of SBP during stress/baseline SBP:r =-0.23, p =0.04) induced by anger recall, while the correlations of the sleep/awake SBP ratio with other parameters of reactivity or recovery in the anger recall or mental arithmetic task were not significant. When subjects were divided into day-shift workers (n =54) and night-shift workers (n =33), the sleep/awake SBP ratio was negatively correlated with relative SBP reactivity (r =-0.41, p =0.02) and relative stress response of SBP (r =-0.48, p =0.006) induced by anger recall, and positively correlated with recovery rate (r =0.34, p =0.06) in the latter group, while these correlations were not significant in the former group. The sleep/awake SBP ratio was inversely correlated with the exercise-induced SBP increase in the day-shift workers (r =-0.30, p =0.03), while this association was not found in the night-shift workers. In conclusion, cardiovascular reactivity triggered by psychological and physical stress in the laboratory may be a weak, but significant, determinant of diurnal BP variation; in addition, work shift (day or night) appears to moderate the relationship between these two pressor mechanisms. (Hypertens Res 2002; 25: 543-551)