Most people are familiar with having their blood pressure checked while sitting in a chair at a doctor’s office. It is one of the most common medical tests in the world.
Doctors use it to look for signs of heart disease, stroke risk, and other health problems. But recent research suggests that this standard method may not always give the full picture of a person’s heart health.
In some people, blood pressure may appear normal while sitting but become dangerously high when lying down. This hidden problem could increase the risk of serious illnesses without people even knowing it.
The research was presented at the American Heart Association’s Hypertension Scientific Sessions in 2023. The study was led by Duc M. Giao, a medical student at Harvard Medical School.
The team examined health information from more than 11,000 adults to understand how blood pressure changes in different body positions and how those changes may affect long-term health.
Blood pressure measures the force of blood pushing against the walls of the arteries. When the pressure stays too high for too long, it can slowly damage blood vessels and force the heart to work harder.
Over time, this raises the risk of heart attacks, strokes, heart failure, kidney disease, and other serious conditions. Because of this, doctors have long considered blood pressure to be one of the most important signs of heart health.
Usually, blood pressure is measured while a person is seated quietly. This has been the standard approach for many years. However, the new study suggests that body position may play a bigger role than many people realized.
Researchers discovered that some people only showed high blood pressure when lying flat on their backs. Their blood pressure looked normal during regular seated testing, meaning the problem could easily go unnoticed during a normal medical visit.
The researchers found that around 16% of participants had this hidden form of high blood pressure. These people had normal readings while sitting but high readings when lying down. This finding surprised the researchers because these people would likely not be diagnosed with high blood pressure during routine testing.
Even more important, the study found that people with high blood pressure only while lying down faced similar health risks as people whose blood pressure was high both while sitting and lying down.
They had increased risks of heart failure, stroke, coronary heart disease, and early death. This means that hidden blood pressure changes during lying down may not be harmless at all.
The study adds to growing evidence that blood pressure is more complicated than a single number measured during one short visit to a clinic. Blood pressure naturally changes throughout the day. It can rise because of stress, physical activity, poor sleep, anxiety, or even drinking coffee.
It can also change depending on whether someone is sitting, standing, or lying down. Some people experience white coat hypertension, where blood pressure rises because they feel nervous in medical settings. Others may have blood pressure that increases mostly during sleep or at night.
Scientists have already known that nighttime blood pressure can strongly affect heart health. During sleep, blood pressure normally falls slightly to allow the heart and blood vessels to rest. If blood pressure stays high at night, it may increase strain on the body for many years without obvious symptoms.
The new study suggests that blood pressure while lying down could also reveal hidden warning signs that are missed during daytime seated testing.
The study mainly involved middle-aged adults, so more research is needed to learn whether the same pattern happens in younger or older people.
Researchers also want to better understand why blood pressure rises in some people when they lie down. It may be linked to changes in blood flow, nerve activity, body fluid movement, or hidden heart and blood vessel problems.
The findings could eventually change how doctors monitor blood pressure in the future. Right now, many clinics only measure blood pressure while patients are seated.
But researchers believe that checking blood pressure in more than one position may help doctors identify people at risk earlier. It may also help explain why some people still develop heart disease or strokes even though their normal blood pressure tests appear healthy.
For people who already have risk factors such as diabetes, obesity, smoking, sleep apnea, or a family history of heart disease, this research may be especially important. These individuals may benefit from more detailed blood pressure monitoring.
Home blood pressure monitors, wearable devices, or overnight monitoring may help provide a fuller picture of how blood pressure changes during daily life and sleep.
Experts say people should not panic if they have only had seated blood pressure tests in the past. However, the study highlights the importance of asking questions and understanding that blood pressure is not fixed. It constantly changes depending on many factors inside the body.
The researchers hope future studies will confirm their findings and help improve medical guidelines. If larger studies continue to show similar results, doctors may one day routinely measure blood pressure in different positions as part of regular heart health checks.
For now, the study offers an important reminder that small details in medical testing can sometimes reveal hidden health risks. A simple extra blood pressure check while lying down could help identify people who need earlier treatment and better protection against heart disease and stroke.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more health information, please see recent studies about added sugar in your diet linked to higher blood pressure, and results showing vitamin D could improve blood pressure in people with diabetes.
Copyright © 2026 Knowridge Science Report. All rights reserved.
