What Time Of Day Is Blood Pressure Lowest?

Overview

Normally, in most people, blood pressure decreases during the nighttime by 10-20% in systolic blood pressure and a lesser amount of diastolic blood pressure compared with time spent awake during the day. Blood pressure rises slowly during late sleep and increases when waking in the morning. There are regulators of blood pressure, including hypothalamic-pituitary-thyroid, mental/emotional stress, the intensity of physical activity, the autonomic and central nervous systems, renal hemodynamics, circadian rhythms of wake/sleep, pineal gland melatonin synthesis, posture, vasoactive peptide and nyctohemeral cycles of ambient temperature. Knowing the 24-hour profile of blood pressure is very important to diagnose and treat certain diseases, for example, patients with secondary hypertension due to renal disease or diabetes show a fall in blood pressure during sleep in a 24-hour blood pressure profile.1

What Is Blood Pressure? 

Blood pressure is the force exercised by circulating blood against the walls of the major blood vessels and arteries in the body.2 It is the pressure of blood in arteries (the vessels that carry your blood from your heart to your brain and the rest of the body). We need a certain amount of pressure to get the blood moving around our bodies. Normally, throughout the day and night, blood pressure goes up and down, and it’s normal for blood pressure to rise while you are moving about. However, when your overall blood pressure is consistently high, even when you are resting, you need to do something about it.

When you have your blood pressure measured, the blood pressure reading shows two numbers. The first is when the pressure is at its highest (systolic pressure), and the second is at its lowest (diastolic pressure). 

  • Systolic blood pressure: is the highest level of blood pressure when the heart beats and contracts to pump blood through arteries.
  • Diastolic pressure: This is the lowest level of your blood pressure – when your heart relaxes between beats.3

The normal blood pressure reading is less than 120\80 mmHg. It is considered elevated when a blood pressure reading shows 120-129 mmHg systolic blood pressure and less than 80 mmHg diastolic pressure. Hypertension (high blood pressure) stage 1 is when blood pressure ranges from 130-139 mmHg systolic or 80-89 mmHg diastolic.4 

Studies have shown that blood pressure readings are higher when measured on the right arm than on the left arm.

Blood Pressure Around The Clock

When Is Blood Pressure The Lowest

Low blood pressure can be normal at night when sleeping or abnormal due to disease. Symptoms of low blood pressure include lack of concentration, blurred vision, feeling cold, rapid and shallow breathing, and fatigue. If you experience any of these symptoms, it’s a good idea to consult with your healthcare providers. You may have more blood pressure when you have a heart problem (abnormal heart rate can stem from a problem with a heart valve, a heart attack, or heart failure), prolonged bed rest, pregnancy, and decreased blood volume 6 A drop in blood pressure that occurs when a person is standing up is called orthostatic hypotension. This can  cause dizziness and lightheadedness. The drop in blood pressure is greater than 20 mmHg for  systolic blood pressure, or more than 10 mmHg in diastolic blood pressure within 3 minutes upon standing after sitting or getting up from a lying supine position.7

When Is Blood Pressure The Highest

As mentioned above, the normal blood pressure increases a few hours before waking up, then rises throughout the morning until reaching the peak around the middle of the day. High blood pressure (hypertension) is the major risk factor for cardiovascular disease, including coronary artery disease, stroke, chronic kidney disease, heart failure, and peripheral artery disease. Abnormally high blood pressure in the first few hours after waking up is called morning hypertension. The higher reading usually decreases within a few hours of waking up.

Another abnormal high blood pressure is isolated systolic hypertension. This is the most  common type of hypertension in older and young adults and arises due to the reduced compliance of the arteries in contrast to long-term vasoconstriction of arteries. This is characterized by an increase in systolic blood pressure.9

When Should You Take A Blood Pressure Reading 

The best times to measure blood pressure are in the morning before you take any blood pressure medication and in the evening. This should be done for a week, once or twice a month, or as your doctor recommends.10 

When you are diagnosed with high blood pressure (hypertension), are a pregnant person, or have risk factors for high blood pressure, you need to monitor your blood pressure, even at home. The American Heart Association recommends an automatic cuff-style, bicep (upper arm) monitor. 

How To Reduce Blood Pressure

High blood pressure is not something that you can notice or feel because usually there are no symptoms with it. Measuring blood pressure regularly is very important.

The following help you to reduce high blood pressure or help to control it if you are diagnosed with hypertension:11

  1. Physical Activity: Physical Activity is any bodily movement produced by contraction of skeletal muscles that increases energy consumption above the resting level. When physical activity is structured, planned and with the intent of maintaining or improving health, this is called exercise. The positive effects of exercise are reducing blood pressure and prevention of hypertension. Examples of exercises include walking, swimming, and aerobic exercise.12 
  2. Maintaining a healthy weight: Being overweight is one of the risk factors for hypertension, so for obese individuals, losing weight can majorly help in reducing their blood pressure.
  3. Eat a healthy and balanced diet and avoid saturated fats: Eat a variety of fruits and vegetables, and avoid food that contains a high level of fat.
  4. Cut down salt: Salt is known to be a silent killer. Don’t cook with salt and avoid processed food that contains salt because salt raises blood pressure.
  5. Don’t drink alcohol 
  6. Take your medication as prescribed: Most people need medication to control their blood pressure.

Summary

Generally, measuring blood pressure is very important in our daily life. High blood pressure (hypertension) is a risk factor for cardiovascular disease. Blood pressure rises in the morning and declines during the nighttime. Knowing the 24-hour blood pressure profile helps us to diagnose many diseases. Monitoring your blood pressure is also very important. An abnormal increase in blood pressure is seen in patients with morning hypertension and isolated systolic hypertension. To reduce your blood pressure, you must engage in physical activity, maintain a healthy weight, eat a healthy and balanced diet, cut down on salt, don’t drink alcohol, and take your medication as prescribed.

References

  1. Smolensky, Michael H., et al. ‘Circadian Mechanisms of 24-Hour Blood Pressure Regulation and Patterning’. Sleep Medicine Reviews, vol. 33, June 2017, pp. 4–16. ScienceDirect, https://doi.org/10.1016/j.smrv.2016.02.003.
  2. High Blood Pressure. https://www.bhf.org.uk/informationsupport/risk-factors/high-blood-pressure.
  3. Low Blood Pressure. https://www.bhf.org.uk/informationsupport/risk-factors/high-blood-pressure/low-blood-pressure.
  4. www.Heart.Org, https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings.
  5. Beaney, Thomas, et al. ‘May Measurement Month 2017: An Analysis of Blood Pressure Screening Results Worldwide’. The Lancet Global Health, vol. 6, no. 7, July 2018, pp. e736–43. ScienceDirect, https://doi.org/10.1016/S2214-109X(18)30259-6.
  6. Low Blood Pressure - When Blood Pressure Is Too Low’. Www.Heart.Org, https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/low-blood-pressure-when-blood-pressure-is-too-low
  7. Sencen, Lisa. ‘Orthostatic Hypotension’. NORD (National Organization for Rare Disorders), https://rarediseases.org/rare-diseases/orthostatic-hypotension/.
  8. Ltd, HealthMatch Pty. ‘Morning Hypertension: Why Is My Blood Pressure Higher In The Morning?’ HealthMatch, 15 Feb. 2022, https://healthmatch.io/high-blood-pressure/why-is-my-blood-pressure-high-in-the-morning.
  9. Tsai, Tsung‐Ying, et al. ‘Isolated Systolic Hypertension in Asia’. The Journal of Clinical Hypertension, vol. 23, no. 3, Nov. 2020, pp. 467–74. PubMed Central, https://doi.org/10.1111/jch.14111.
  10. Monitoring Your Blood Pressure at Home’. Www.Heart.Org, https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings/monitoring-your-blood-pressure-at-home.
  11. How to Reduce Your Blood Pressure: 6 Top Tips. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/research/blood-pressure/blood-pressure-tips.
  12. Diaz, Keith M., and Daichi Shimbo. ‘Physical Activity and the Prevention of Hypertension’. Current Hypertension Reports, vol. 15, no. 6, Dec. 2013, pp. 659–68. PubMed Central, https://doi.org/10.1007/s11906-013-0386-8.

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Malaz Ameer Ata Almanan

Medical Student - University of Bahri, Khartoum, Sudan

Malaz Ameer Ata Almanan Mohammed. 4th year medical student. Researcher enthusiast. Passionate about ophthalmic surgery. I would like to be ophthalmologist.

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