Circadian Variation Of Blood Pressure In The Population At Large

Ambulatory blood pressure (ABP) measurement has several advantages. ABP readings are obtained outside the medical environment and are free of the so-called white coat effect (1,2) often seen when the blood pressure (BP) is conventionally measured. Therefore, the average BP level on ABP measurement provides a better estimate of a subject’s usual BP than conventional readings (3). In addition, BP is recorded during the habitual daily activities, both working and resting periods, and during episodes of emotional stress and sleep. The way in which a subject’s BP is modulated throughout the day to cope with these various levels of physical and emotional activity may provide meaningful pathophysiological information (4). Some investigators have demonstrated that the amplitude of the diurnal BP profile is characteristic for an individual (5), or that a blunted or absent nocturnal fall in BP is correlated with a worse cardiovascular prognosis (4,6–8). These views explain the growing interest in methods to describe the diurnal BP profile and its determinants.