Ambulatory blood pressure monitoring permits measurement of blood pressure throughout the day and night. A normal patient should have a drop in blood pressure ("dip") at night. A patient who does not show this drop in blood pressure ("nondipper") may have increased cardiovascular morbidity.


Patients were classified by:

(1) nocturnal blood pressure status

(2) nocturnal blood pressure fall


Nocturnal BP Status

Blood Pressure (S/D)


< 125/75 mm Hg


>= 125/75 mm Hg


mean arterial blood pressure =

= ((systolic blood pressure) + (2 * (diastolic blood pressure))) / 3


percent nocturnal blood pressure fall =

= ((daytime mean arterial BP) - (nighttime mean arterial BP)) / (daytime mean arterial blood pressure) * 100%


Percent Nocturnal Blood Pressure Fall


>= 20% fall

extreme dipping

10 to 19.9% fall

normal dipping

0 to 9.9% fall

attenuated dipping

rise (negative fall)

rising (nondipping)


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