"Blood pressure (BP) always varies over time, including beat-by-beat, trigger-induced, orthostatic, diurnal, day-by-day, weekly, seasonal, and age-related variations. Of these different BP variability components, circadian rhythm is the central component of individual BP variability, and there is a large body of accumulating evidence highlighting the importance of this parameter. Basic circadian rhythm forms the basis of individual diurnal BP variation (Figure 1.1) 1. The circadian rhythm of BP is physiologically determined partly by the intrinsic rhythm of central and peripheral clock genes, which regulate the neurohumoral factor and cardiovascular systems, and partly by the sleep-wake behavioral pattern, and is associated with various pathological conditions. In addition to different patterns of circadian rhythm, short-term BP variability such as morning BP surge (MBPS), physical or psychological stress-induced daytime BP, and nighttime BP |