Effects of nighttime alcohol intake on evening and next morning home blood pressure in Japanese normotensives

Home blood pressure (HBP) is usually measured in the morning and evening, but the evening HBP tends to be influenced by an individual's behavior pattern, such as bathing and drinking, which are often seen in the Japanese. In this study, in order to elucidate the influence of nighttime drinking on the evening and next morning HBP and heart rate (HR), HBP measurement was performed in Japanese normotensives under conditions in which the influence of bathing was minimized. Among 700 registered volunteers, 245 normotensives (189 male, 56 female, mean age; 35.8 +/- 0.5 years old) whose data consisted of a combination of drinking and non-drinking on workdays were selected. A semi-automatic device was lent to all participants, and they were asked to perform triplicate morning and evening measurements on seven consecutive days between October 16, 2002, and November 13, 2002. The differences in evening HBP and HR between the drinking and non-drinking days were calculated, as were the differences in the next morning HBP and HR. Only data of evening HBP measured at least 30 min after bathing were accepted. Evening SBP and DBP on drinking days were significantly lower (2.5 +/- 0.5 mmHg, 3.1 +/- 0.5 mmHg) than those on non-drinking days. On the other hand, evening HR on drinking days was significantly higher (7.7 +/- 0.8 b.p.m.) than that on non-drinking days. Although there was no difference in morning SBP after days with and without drinking, morning DBP the day after drinking was slightly (0.8 +/- 0.3 mmHg) but significantly lower than that the day after non-drinking. Morning HR the day after drinking was significantly higher (2.4 +/- 0.4 b.p.m.) than that after non-drinking. Because nighttime drinking influenced the evening HBP even in normotensives, it was suggested that morning HBP could give more stable values than evening HBP in Japanese people.