It’s estimated that nearly half of all adults in the United States have high blood pressure, also called hypertension.

Because the condition often has no symptoms, getting your blood pressure checked regularly is an important way to determine whether you have hypertension.

But did you know that your blood pressure can change depending on your position? Your blood pressure readings can fluctuate depending on whether you’re sitting or lying down.

In this article, we’ll explore what’s known about how your position may affect your blood pressure and what you can do to keep it under control.

Blood pressure is the force that’s exerted by your blood on the walls of your arteries. Arteries are a type of blood vessel that carry oxygen-rich blood away from your heart, delivering it to the organs and tissues of your body.

Blood pressure is measured in millimeters of mercury (mm Hg). A blood pressure reading is made up of two numbers:

  • Systolic. This is the first number of your blood pressure reading. It’s the pressure placed on your arteries when your heart beats.
  • Diastolic. This is the second number of your blood pressure reading. It measures the pressure on your arteries between heartbeats.

Now let’s look at what’s a normal blood pressure reading and what’s considered high.

High blood pressure increases your risk of serious complications like heart attack, stroke, and chronic kidney disease. That’s why it’s important to take steps to keep your blood pressure within a healthy range.

It’s known changing positions can impact your blood pressure reading. However, there’s some disagreement about whether readings are higher or lower when you’re lying down.

Several older studies found that blood pressure was higher among study participants while they were lying down compared to sitting. One of these, a 2008 study, included 6,485 healthy volunteers.

However, the results of several newer studies have suggested blood pressure may be lower while lying down than when sitting:

  • A 2017 study of 967 men and 812 women looked at the effect of body position on blood pressure. It found that diastolic readings were higher in both sexes when sitting but only on the first reading. Repeated blood pressure readings didn’t find the same difference between sitting and lying down.
  • A study from 2018 investigated blood pressure readings in a cohort of 1,298 men. It found that both systolic and diastolic blood pressure readings were significantly higher in the seated position than when lying down.
  • A 2017 study of 280 people with high blood pressure found that the average systolic and diastolic blood pressure readings were lower when measured while lying down than when measured in a sitting position. It’s important to note that the participants in this study had their blood pressure taken after resting for 10 minutes, which may have influenced the readings.

Lower blood pressure while lying down makes sense when you think of your heart as a pump. When you’re lying down, most parts of your body are at the same level as your heart. Because of this, your heart doesn’t have to work as hard to circulate blood throughout your body.

So why are there variations in the findings, especially with the older studies? Investigators suggest that the variations could be due to differences in the populations studied, such as age or underlying health conditions. The technique and order of the blood pressure measurements could also play a role.

Although there may be minor changes based on your body position, there’s currently no consensus in the medical community that blood pressure is significantly lower or higher in one position over another. The only exception may be in situations where someone has an underlying health condition.

For consistency, medical experts suggest that your blood pressure readings should always be taken in the same position. This makes it easier to compare your readings and to notice any changes.

Your blood pressure can also change as you move from one position to another. This may be particularly noticeable when you move from a sitting or lying position to a standing position.

When you stand, gravity causes blood to pool in your lower body. This can cause a temporary drop in blood pressure. However, your body has a way to adjust to this change.

Certain reflexes in your body send a signal to your brain when a drop in blood pressure is detected. Your brain then tells your heart to beat faster in order to pump more blood. This works to stabilize your blood pressure.

However, sometimes this process can be interrupted, causing the drop in blood pressure to last longer than normal. When this happens, there’s a delay in blood flow to your brain. As a result, you may feel lightheaded, dizzy, or faint for a short while after you stand.

This condition is called orthostatic hypotension or postural hypotension. It can be caused by a variety of factors, including:

The American Heart Association recommends sitting down to take your blood pressure. They also note that while there are differences in the right arm versus the left arm, these are small and only cause a variation of 10 mm Hg or less.

Additional posture-related factors can also affect your blood pressure readings. To get an accurate reading at your doctor’s office try to:

  • Sit up straight, with your back supported by the back of your chair.
  • Make sure your feet are flat on the floor. Avoid crossing your legs or ankles.
  • Place your arm at the level of your heart, supporting it on a table or armrest. You may need to use a pillow to help get the right elevation.

There are some instances where you may have your blood pressure taken lying down. An example of this is if you’ve been hospitalized and can’t sit up.

If you have orthostatic hypotension, your blood pressure may be taken in two different positions — sitting and standing. This can help your doctor monitor how your blood pressure changes when you move from a sitting to a standing position.

If you need to measure your blood pressure at home, the following tips may be helpful in getting accurate readings:

  • Carefully choose your monitor. An automated, cuff-style monitor that fits around your upper arm is recommended by the American Heart Association. When choosing a monitor, check the:
    • Fit. Make sure that the cuff fits over your upper arm.
    • Validation. Check to see if the monitor is certified by a respected organization, like the Association for the Advancement of Medical Instrumentation or the British Hypertension Society. If it’s for an older adult, a child, or a pregnant woman, make sure the monitor is specifically validated for these groups.
    • Accuracy. Bring your monitor along with you to your next doctor’s visit. That way, you can make sure that it’s giving the same readings as your doctor’s equipment.
  • Take your blood pressure twice per day. Take the first reading in the morning, before eating or taking medications but not right after waking. Take your second reading in the evening. Aim to take the readings around the same time each day.
  • Prepare beforehand. Use the bathroom prior to taking your reading. Avoid caffeine, alcohol, and tobacco in the 30-minute period prior to taking a reading. Also avoid exercise or strenuous activity during this time.
  • Position properly. Try to use the same chair each time. Make sure your back is straight and supported by the back of the chair. Keep your feet flat on the floor.
  • Relax. Sit quietly and calmly in the chair for 5 minutes before taking your reading. Avoid talking or thinking about anything stressful.
  • Use the same arm. Use the same arm each time you take a reading. Rest your arm on a tabletop or a pillow to raise it to the level of your heart. Also, place the cuff over bare skin and not over your clothing.
  • Take repeat readings. Wait a few minutes after taking a reading before taking another. This helps to check if your monitor is accurate. It can also help you to confirm a reading.
  • Record results. Use a journal to keep a log of your blood pressure readings. Bring this with you when you visit your doctor.

If you notice that you’ve been having consistently high readings, contact your doctor. Your treatment plan may need to be adjusted.

Seek immediate medical attention if a reading exceeds 180/120 mm Hg.

There are specific lifestyle habits that may help reduce your risk for hypertension. Your doctor may recommend some of these changes before prescribing medication.

Your body position can impact your blood pressure reading. According to older research, blood pressure may be higher while lying down. But more recent studies have found that blood pressure may be lower while lying down versus sitting.

Currently, the American Heart Association recommends that blood pressure readings be taken when you’re sitting down. However, in some cases you may have your blood pressure taken while lying down or while standing.

For consistency, medical experts suggest that your blood pressure readings should always be taken in the same position.

Taking blood pressure at home is a valuable tool for early diagnosis or monitoring the effectiveness of your treatment. Talk with your doctor if you have questions about home blood pressure monitoring or if you have consistently high readings.