Stress, Salt Excretion, and Nighttime Blood Pressure

The study will examine urinary sodium excretion induced by psychological stress and its diurnal pattern as a novel biological mechanism that may underlie an abnormal diurnal pattern of blood pressure. The study will test the hypotheses that lower stress-induced sodium excretion is associated with an abnormal diurnal pattern of sodium excretion, and that an abnormal diurnal pattern of sodium excretion is associated with an abnormal diurnal pattern of blood pressure. Primary Aim 1: To examine the association between urinary sodium excretion after provoked psychological stress and the diurnal pattern of sodium excretion. Primary Aim 2: To examine the association between the diurnal pattern of sodium excretion and the diurnal pattern of BP. Secondary Aim: To examine whether the association between urinary sodium excretion after provoked stress and the diurnal pattern of sodium excretion is modified by ecological momentary levels of perceived stress, experienced during the daytime period. Exploratory Aim: To determine the socio-demographic, behavioral, and psychological traits, chronic stress, and biological stress-related factors that are associated with lower stress-induced sodium excretion. Identification of these factors will help determine who is at risk for having a differential sodium excretion response to psychological stress.