[Morning rise in blood pressure: before or following awakening?].

The coincidence of the circadian peak of cardiovascular events with the morning blood pressure rise suggests causal connections. Rapidly acting antihypertensives taken before getting up may attenuate the increase early enough, if the onset does not occur before awakening. In 111 normotensives and in 109 subjects with untreated essential hypertension ambulatory blood pressure monitoring was performed to study whether the onset of the blood pressure rise occurs before or after waking up. The individual 24 h blood pressure profiles obtained by intermittent readings at intervals of 15 minutes were synchronized by the time of waking up. The resulting blood pressure curves showed no substantial blood pressure rise during sleep, but steep increases after awakening: Within the first hour after waking up blood pressure increased from 107.3 + 11.4/62.3 +/- 9.6 mm Hg (mean + sd) to 121.4 +/- 16.0/75.3 + 12.6 mm Hg in normotension and from 124.7 + 16.0/72.7 + 12.2 mm Hg to 140.3 + 17.2/84.5 + 13.3 mm Hg in hypertension. The velocity of this increase was dependent on the lag between waking up and getting up. There was no phase difference between early morning blood pressure and heart rate rises. Thus to attenuate the morning blood pressure increase, rapidly acting drugs after awakening may be considered instead of long acting antihypertensives administered prior to sleep.