Shorter-term alternatives to 24-hour monitoring of BP were analyzed in six hypertensive patients. Average BPs during the 24-hour period were lower than averages during a two-hour morning period or those based on either three readings or a single reading taken at 8 AM. The systolic and diastolic BP two-hour averages correlated more strongly with the 24-hour averages than did the three-reading or single-reading alternatives. Thus, the average of serial BP readings obtained during a two-hour morning period is a consistent predictor of the whole-day BP and represents it more closely than the conventionally used single reading.
Weber MA, Drayer JIM, Wyle FA, Brewer DD. A Representative Value for Whole-Day BP Monitoring. JAMA. 1982;248(13):1626-1628. doi:10.1001/jama.1982.03330130074032