Epidemiologic studies have demonstrated that the peak incidence of most types of
cardiovascular disease follows a circadian (24 h) pattern. Ambulatory monitoring studies
have documented a reproducible 24 h rhythm for blood pressure, characterized by a period
of low values during sleep, an early-morning increase in pressures, and a plateau period
while the individual is awake and active. Hypertensive patients who display the typical
nocturnal decrease in blood pressure are termed 'dippers', whereas patients in whom the …