Ambulatory blood pressure monitoring is a way of evaluating and controlling hypertension that is done 24 hours a day, 7 days a week. Ambulatory blood pressure monitoring produces a large number of measurements over a long period of time. Throughout the day, scans are usually obtained every 20 to 30 minutes, and at night, readings are taken every hour. Simultaneously, your heart rate can be determined. Changes in heart rate and blood pressure are calculated, as well as the BP relative proportion and some other information.