Blood pressure is a dynamic feature of pumping blood. BP readings vary. BP tends to be lowest in the morning and highest in the late afternoon. BP will rise with exertion and may be very high briefly with vigorous exercise.

Self monitoring of blood pressure makes sense for several reasons - you can learn more about how your pressure reacts to food, events, and time of day. You can average many readings to get a true estimate of BP. A few high readings in a physicians office may be an artifact and many readings at home will show a lower average.

Systolic Pressure is the first, higher reading - a transient pressure peak when the heart is contracting and forcing blood through the arterial system.

Diastolic pressure is the second lower reading - the sustaining pressure in the arterial system when the heart is filling with blood.