Seasonal Influence on Blood Pressure in Elderly Normotensive Subjects

The aim of this study was to examine whether or not fluctuations in blood pressure (BP) differ by season. Subjects were 45 elderly individuals (20 men and 25 women; mean age, 66.5+/-4.9 [SD] years). Each subject's BP was recorded with an ambulatory BP monitoring device for 24 h during each of the four seasons. Subjects also wore a portable weather meter to obtain ambient temperature, relative humidity, and barometric pressure simultaneously with BP. The relationships between meteorologic values and BP were investigated at various parts of the day. Seasonal differences in BP fluctuation around wake-up-time were analyzed by means of the Tukey's test. The difference between the pre-wake-up-time systolic BP and the wake-up-time systolic BP was significantly greater in winter than in summer (8.7 mmHg greater, p