Online CME . Chronobiologists have identified daily, monthly, and seasonal rhythms. The focus for this newsletter will be on the 24-hour or circadian rhythms. A characteristic profile of blood pressure fluctuation over a 24-hour period is well described.
Levels begin to increase after that and before awakening.
There is a sharp increase in blood pressure and heart rate in the early morning prior to awakening, certainly upon awakening and upon getting up. Blood pressure may peak in the morning and then stay at that level during the afternoon and evening. In some patients it continues to rise gradually, peaking in the late afternoon. This has been described more consistently in African-Americans with hypertension, and in diabetics. Increased cardiovascular risk has been associated with daytime systolic and diastolic blood pressure, but it is also probably even more closely correlated with total 24-hour pressure load.