Circadian variation of blood-pressure.

Continuous intra-arterial blood-pressure and electrocardiogram recordings were obtained in twenty hypertensive and five normotensive ambulant patients. Blood-pressure was highest mid-morning and then fell progressively throughout the remainder of the day. Blood-pressure was lowest at 3 A.M. and began to rise again during the early hours of the morning before waking. These findings may have important consequences with regard to the therapeutic management of hypertension.