Parallel morning and evening surge in stroke onset, blood pressure, and physical activity

Background and Purpose-A circadian variation with a morning peak on waking and arising is known to occur in both blood pressure (BP) and cardiovascular event onset. A second peak in BP has been described to occur after an afternoon sleep (siesta). This study was designed to investigate the hypothesis that the 2-peak diurnal variation of BP is dependent on physical activity and occurs in parallel with the diurnal variation of stroke onset. Methods-The diurnal variation of stroke onset was compared with the diurnal variation of BP, pulse rate (PR), and physical activity in 3 independent groups of Greek hypertensives 51 to 80 years of age (633 stroke patients, 379 subjects with 24-hour ambulatory BP monitoring, and 50 subjects with 24-hour physical activity monitoring through wrist devices). Results-The diurnal variation of stroke onset, BP, and PR all showed 1 morning and 1 evening peak with a decline in the afternoon and at night that occurred in parallel with the diurnal variation in physical activity (P<0.001 for differences among morning, afternoon, evening, and nighttime intervals in BP, PR, activity, and stroke). The afternoon decline in BP, PR, and activity was significant only in subjects with a siesta. Conclusions-The 2-peak diurnal variation in stroke onset occurred in parallel with the variation in BR PR, and physical activity. These data support the hypothesis that an abrupt change in physical activity is not only a major determinant of the 2-peak diurnal variation of BP but also an important triggering factor for a cerebrovascular event.