Table of ContentsView AllTable of ContentsWhy Blood Pressure MattersSystolic Blood PressureDiastolic Blood PressureImproving Accuracy
Table of ContentsView All
View All
Table of Contents
Why Blood Pressure Matters
Systolic Blood Pressure
Diastolic Blood Pressure
Improving Accuracy
Ablood pressure (BP)reading consists of two numbers: systolic vs. diastolic pressure.
For example, a blood pressure reading considered normal for most healthy adults is usually below 120/80, which is reported as “120 over 80.” The systolic pressure is 120 and the diastolic pressure is 80. Children and teens may have slightly lower normal blood pressure. Older adults may also have higher or lower blood pressures that are considered normal.
Both numbers give important information about your health. However, your healthcare provider might give more importance to high systolic pressure to determine your risk of heart disease.
This article explains the differences between systolic and diastolic blood pressure; why both numbers are important; and what your blood pressure readings mean.
Is My Blood Pressure Normal?
Why Your Blood Pressure Matters
When the heart beats, blood pulses through thearteriesto travel throughout the body. However, it is not a steady stream like you might see from a garden hose.
The pulse of the blood flow and the pressure it exerts change from moment to moment. It’s highest during the heartbeat (systolic pressure) and lowest between heartbeats (diastolic pressure).
Providers measure blood pressure using these numbers because it is a standard way of describing the force of the pulsing blood.
Your systolic and diastolic blood pressures are both important. If the readings are too high, you could have high blood pressure.If the readings are too low, there may not be enough blood flowing to your brain and other organs.
Furthermore, if there are changes in the difference between the two numbers, it’s a clue that there could be aheart conditionor other health problem.
How Can You Tell If You Have High Blood Pressure?
During a heartbeat, the heart pushes blood out into thearteries. Systolic pressure is the measure of this pressure within the arteries while the heart beats. This phase, known as systole, is the point at which blood pressure is the highest.
Systolic blood pressure is considered normal when the reading is below 120 mmHg (millimeters of mercury) while a person is sitting quietly at rest.
High Systolic Blood Pressure
The heart muscle pushes out blood with higher pressure when a person isexercising, under stress, or at any time when the heart rate is increased. The systolic pressure goes up with it.
In these cases, the increased pressure is normal. However, when the pressure is high while a person is resting, that is not normal and is considered high blood pressure.
Since your blood pressure can go up when you’re active, it’s important to take your blood pressure during periods of quiet rest to accuratelydiagnosehigh blood pressure (hypertension).
Within the high systolic pressure range, there are different stages:
Your healthcare provider will help you determine the best course of action for treating your high systolic BP.
What Does It Mean If Only Your Systolic Blood Pressure Is High?
Low Systolic Blood Pressure
Systolic pressure can also be too low. When the reading is below 90 mmHg, it’s calledhypotension. This can causelightheadedness,dizziness, orfainting. If low blood pressure is not treated, it may cause organs like the kidneys to start shutting down.
Systolic hypotension can occur if the amount of blood in your body becomes too low. For example, low blood pressure can happen when you are severely dehydrated or when you have major bleeding. In these cases, there just isn’t enough blood to push through the body.
Low blood pressure can also happen if the heart muscle is too weak to push blood normally—for example, if the heart muscle is damaged (cardiomyopathy) or if the arteries suddenly widen too much (as invasovagal syncope, a reflex that causes fainting).
Sometimes, low blood pressure happens when you change positions suddenly. You may feel dizzy when you stand up because gravity is pulling blood down toward your feet. This is a common condition calledorthostatic hypotension.
Pulse Pressure Predictions: What Ranges Suggest About Your Health
The heart rests between beats so it can refill with blood. The pause between beats is called “diastole.” Your diastolic blood pressure is the measurement during this pause before the next heartbeat.
Normal diastolic blood pressure during quiet rest is below 80 mmHg.If you have high blood pressure, the diastolic number is often higher even during quiet rest. Diastolic blood pressure is considered dangerously low when it is 60 mmHg or lower and dangerously high when it is 110 mmHg or over. If you receive multiple readings with these numbers, you should call your healthcare provider.
Low diastolic pressure may be seen with dehydration or with severe bleeding.It also may happen if the arteries relax and widen.
There are also multiple stages of high diastolic blood pressure:
Improving Blood Pressure Reading Accuracy
Your systolic and diastolic pressures change depending on your activity level, stress, fluid intake, and other factors.
It’s important to limit how these other factors might change your pressure when you’re taking a blood pressure reading.
For the most accurate reading, follow these steps when checking your blood pressure:
Measuring blood pressure this way is a challenge in a busy provider’s office. Your healthcare provider might suggest you take your blood pressure at home.
What Time of Day Should I Check My Blood Pressure?
Many experts suggest recording blood pressure over an extended time (which can include repeating the measurements at home) before diagnosing high blood pressure.
In addition, your blood pressure will be different throughout the day. It tends to be highest in the morning and lower at night.
Your provider may want you to use ablood pressure monitorto measure your blood pressure multiple days a day—usually once in the morning and once in the afternoon or evening. Try to avoid taking it right when you wake up in the morning or right after dinner.
Instead, try to take your morning reading before your breakfast (especially if you drink coffee or take medication) and your evening reading when you’re getting ready for bed (and again, before you take any medications).
Once you decide what time you’ll check your blood pressure, it’s important to be consistent. You’ll get the most accurate results and comparisons if you take your blood pressure at about the same time every day.
White Coat Syndrome and High Blood Pressure (HBP): What to Know
Summary
Your blood pressure is a measurement of the pressure in your arteries while your heart is beating (systolic) and between beats (diastolic). Both of these values are important for diagnosing and managing high blood pressure.
Systolic and diastolic blood pressure are also important to know for treating a range of conditions, including heart disease or severe blood loss. It’s important to get an accurate blood pressure reading under calm, quiet conditions.
Why Your Blood Pressure Changes Throughout the Day
When Is the Best Time to Take Your Blood Pressure?
12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.University of Iowa Stead Family Children’s Hospital.Vital Signs: Normal blood pressure (PICU chart)American Heart Association.Which blood pressure number matters most? The answer might depend on your age.Centers for Disease Control and Prevention.Measure Your Blood Pressure.Tang KS, Medeiros ED, Shah AD.Wide pulse pressure: A clinical review.J Clin Hypertens. 2020;22(11):1960-1967. doi:10.1111/jch.14051American Heart Association.Understanding blood pressure readings.U.S. Department of Health & Human Services. National Institutes of Health.Orthostatic Hypotension.Watso JC, Farquhar WB.Hydration status and cardiovascular function.Nutrients. 2019;11(8):1866. doi:10.3390/nu11081866American Heart Association.Monitoring Your Blood Pressure at Home.Zeng W, Chan SW, Tomlinson B.Patient preferences for ambulatory blood pressure monitoring devices: Wrist-type or arm-type?Shimosawa T, ed.PLoS ONE. 2021;16(8):e0255871. doi:10.1371/journal.pone.0255871UT Southwestern Medical Center.5 tips for taking your blood pressure at home.Harvard Medical School.When is the best time to check your own blood pressure?.Harvard Medical School.When is the best time of day to check blood pressure at home?.Additional ReadingMuntner P, Shimbo D, Carey RM, et al.Measurement of blood pressure in humans: a scientific statement from the American Heart Association.Hypertension. 2019;73(5). doi:10.1161/HYP.0000000000000087
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.University of Iowa Stead Family Children’s Hospital.Vital Signs: Normal blood pressure (PICU chart)American Heart Association.Which blood pressure number matters most? The answer might depend on your age.Centers for Disease Control and Prevention.Measure Your Blood Pressure.Tang KS, Medeiros ED, Shah AD.Wide pulse pressure: A clinical review.J Clin Hypertens. 2020;22(11):1960-1967. doi:10.1111/jch.14051American Heart Association.Understanding blood pressure readings.U.S. Department of Health & Human Services. National Institutes of Health.Orthostatic Hypotension.Watso JC, Farquhar WB.Hydration status and cardiovascular function.Nutrients. 2019;11(8):1866. doi:10.3390/nu11081866American Heart Association.Monitoring Your Blood Pressure at Home.Zeng W, Chan SW, Tomlinson B.Patient preferences for ambulatory blood pressure monitoring devices: Wrist-type or arm-type?Shimosawa T, ed.PLoS ONE. 2021;16(8):e0255871. doi:10.1371/journal.pone.0255871UT Southwestern Medical Center.5 tips for taking your blood pressure at home.Harvard Medical School.When is the best time to check your own blood pressure?.Harvard Medical School.When is the best time of day to check blood pressure at home?.Additional ReadingMuntner P, Shimbo D, Carey RM, et al.Measurement of blood pressure in humans: a scientific statement from the American Heart Association.Hypertension. 2019;73(5). doi:10.1161/HYP.0000000000000087
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
University of Iowa Stead Family Children’s Hospital.Vital Signs: Normal blood pressure (PICU chart)American Heart Association.Which blood pressure number matters most? The answer might depend on your age.Centers for Disease Control and Prevention.Measure Your Blood Pressure.Tang KS, Medeiros ED, Shah AD.Wide pulse pressure: A clinical review.J Clin Hypertens. 2020;22(11):1960-1967. doi:10.1111/jch.14051American Heart Association.Understanding blood pressure readings.U.S. Department of Health & Human Services. National Institutes of Health.Orthostatic Hypotension.Watso JC, Farquhar WB.Hydration status and cardiovascular function.Nutrients. 2019;11(8):1866. doi:10.3390/nu11081866American Heart Association.Monitoring Your Blood Pressure at Home.Zeng W, Chan SW, Tomlinson B.Patient preferences for ambulatory blood pressure monitoring devices: Wrist-type or arm-type?Shimosawa T, ed.PLoS ONE. 2021;16(8):e0255871. doi:10.1371/journal.pone.0255871UT Southwestern Medical Center.5 tips for taking your blood pressure at home.Harvard Medical School.When is the best time to check your own blood pressure?.Harvard Medical School.When is the best time of day to check blood pressure at home?.
University of Iowa Stead Family Children’s Hospital.Vital Signs: Normal blood pressure (PICU chart)
American Heart Association.Which blood pressure number matters most? The answer might depend on your age.
Centers for Disease Control and Prevention.Measure Your Blood Pressure.
Tang KS, Medeiros ED, Shah AD.Wide pulse pressure: A clinical review.J Clin Hypertens. 2020;22(11):1960-1967. doi:10.1111/jch.14051
American Heart Association.Understanding blood pressure readings.
U.S. Department of Health & Human Services. National Institutes of Health.Orthostatic Hypotension.
Watso JC, Farquhar WB.Hydration status and cardiovascular function.Nutrients. 2019;11(8):1866. doi:10.3390/nu11081866
American Heart Association.Monitoring Your Blood Pressure at Home.
Zeng W, Chan SW, Tomlinson B.Patient preferences for ambulatory blood pressure monitoring devices: Wrist-type or arm-type?Shimosawa T, ed.PLoS ONE. 2021;16(8):e0255871. doi:10.1371/journal.pone.0255871
UT Southwestern Medical Center.5 tips for taking your blood pressure at home.
Harvard Medical School.When is the best time to check your own blood pressure?.
Harvard Medical School.When is the best time of day to check blood pressure at home?.
Muntner P, Shimbo D, Carey RM, et al.Measurement of blood pressure in humans: a scientific statement from the American Heart Association.Hypertension. 2019;73(5). doi:10.1161/HYP.0000000000000087
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