It is also helpful in patients with apparent drug resistance, hypotensive symptoms with antihypertensive medications, episodic hypertension, or autonomic dysfunction. Ambulatory BP values are usually lower than office readings. Individuals with hypertension have an average BP of 4135/85 mm Hg when awake and 4120/75 mm Hg during sleep. The level of BP measurement by using ABPM correlates better than office measurements in patients with target organ injury. ABPM also provides data on the percentage of BP readings that are elevated, the overall BP load, and the extent of BP reduction during sleep. In most individuals, BP decreases by 10 to 20% during the night; those in whom such reductions are not present are at increased risk for cardiovascular events. Home BP monitoring: Home measurement devices should be checked regularly for accuracy. European Society of 1. Refers to http://www.dableducational.org/ for UK available ABPM and home measuring devices. 2. Details proper equipment and technique. 3. Outlines accepted and potential clinical indications for ABPM. Out-of-office BP measurements are now recommended as part of the proper diagnosis of hypertension. ABPM should be offered to confirm the diagnosis of hypertension if two BP measurements during an office consultation are X140/90 mm Hg. If ABPM is used, at least two measurements per hour must be taken during waking hours (08:00 to 22:00). The average value at least 14 measurements taken during the waking hours is needed to confirm the diagnosis of hypertension. Home BP monitoring is a suitable alternative to ABPM and requires two consecutive BP measurements a minute apart in the seated position, taken twice daily (usually morning and evening) for at least 4 days (but ideally 7). The first day s measurements are discarded and the average of the remaining measurements are used to confirm a diagnosis of hypertension. 