24-Hour Ambulatory Blood Pressure Monitoring (2025)

What is ambulatory blood pressure monitoring?

Ambulatory blood pressure monitoring is a way of measuring and managing high blood pressure. High blood pressure (hypertension) means your top number (systolic blood pressure) is at least 130 mmHg (millimeters of mercury), and/or your bottom number (diastolic blood pressure) is at least 80 mmHg.

Ambulatory blood pressure monitoring records your blood pressure (BP) readings over a 24-hour period, whether you’re awake or asleep. This happens outside your healthcare provider’s office, as you go about your daily life. You wear a cuff on your arm and a small device attached to a strap or belt.

You may be more familiar with having your BP checked in a healthcare provider’s office during an appointment. In this case, your provider uses a device called a sphygmomanometer to measure and record one or two readings during your visit.

Ambulatory blood pressure monitoring takes dozens of readings over a continuous period. In most cases, the device records readings every 15 to 30 minutes during the day and every 60 minutes at night. The device also measures your heart rate (how fast your heart is beating). Your provider uses this data to calculate your average BP over the 24-hour period. They also calculate changes in BP and heart rate, BP distribution pattern and other statistics.

Why is ambulatory blood pressure monitoring used?

Healthcare providers use this method for many reasons, including to:

• Confirm a diagnosis of hypertension.
• Identify how changes in your blood pressure relate to your daily activities and sleep patterns. Usually, your systolic BP (your top number) decreases about 10% to 20% when you sleep. However, this isn’t always the case. Your systolic BP may stay the same or go up.
• See how well your blood pressure medication is controlling your high BP. Your medication may not control your BP throughout the entire day and night. Your provider may need to adjust your dosage or the times that you take your pills, depending on your BP patterns. Or, you may need more than one drug to stabilize your BP.
• Identify changes in your blood pressure readings at your healthcare provider’s office versus at home. These changes can help show your level of risk for cardiovascular disease.

Ambulatory blood pressure monitoring can detect abnormal changes in BP that might otherwise go unnoticed. It’s a useful way to detect different blood pressure patterns, as listed below.

White coat hypertension

Some people who have normal blood pressure at home have elevated blood pressure in a healthcare setting. This is known as white coat hypertension, or white coat syndrome. It can lead to a hypertension diagnosis when your blood pressure is actually normal. White coat hypertension occurs in 10% to 30% of people with elevated BP readings in healthcare settings.

Current guidelines don’t recommend treatment when ambulatory monitoring shows normal readings outside your provider’s office. However, research continues to explore this topic. White coat hypertension may still indicate a blood pressure problem. So, you and your provider should keep an eye on it.

Sustained hypertension

This refers to BP readings that are elevated whether you’re in your provider’s office or at home. Researchers have linked this condition to an increased risk of heart and kidney damage, as well as stroke.

Masked hypertension

This occurs when your BP reading is normal at your provider’s office, but elevated when you’re at home. It may affect up to 30% of adults who have normal BP readings at their provider’s office. You may face a higher risk of developing masked hypertension if you have kidney disease, diabetes or obstructive sleep apnea.

Nocturnal hypertension

This means your BP goes up when you sleep. Nocturnal hypertension affects at least 2 in 10 white people, and about 4 in 10 Black people. It’s more common among people who have diabetes or kidney disease. Research continues to explore how nocturnal high BP relates to cardiovascular disease.

Who needs ambulatory blood pressure monitoring?

Ambulatory blood pressure monitoring can help a wide range of people. Your healthcare provider may recommend ambulatory blood pressure monitoring if you:

• Have high blood pressure based on readings at your provider’s office, but you haven’t yet started treatment.
• Need changes to your blood pressure medications.
• Still have high blood pressure despite medications.
• Are taking other medications that may affect your blood pressure.
• Have fainting episodes or hypotension (low blood pressure).
• Have high blood pressure during pregnancy.

Are ambulatory blood pressure monitors accurate?

Yes. Ambulatory blood pressure monitoring is an accurate and effective way to measure your blood pressure. It gives your healthcare provider better data compared with only measuring your BP at your medical appointments.

Ambulatory blood pressure monitoring provides frequent readings of your blood pressure and heart rate over a 24-hour period.