Blood pressure is, as the name implies, the pressure of blood circulating through the vessels on the walls of blood vessels. It’s one of the most important and commonly used medical measurements, affecting our health in a number of ways.

Your blood pressure is measured with 2 numbers: the systolic pressure (the high number), is the force with which your heart is pumping blood around the body. The diastolic pressure (lower number) is the resistance to blood flow in the vessels, or when the heart muscle is relaxed. Systole is when the heart contracts, diastole is when it doesn’t — what’s why the diastole is always lower. Both are measured in millimeters of mercury (mmHg).

As a general rule, high blood pressure is considered 140/90mmHg or higher, and ideal blood pressure is considered to be between 90/60mmHg and 120/80mmHg. However, everyone’s blood pressure is different, and even your own blood pressure can vary significantly over long periods of time. Even within the same day, there can be variations. Let’s have a look.

Does blood pressure vary across the day?

Blood pressure fluctuates naturally throughout the day according to a fairly regular pattern. This is absolutely normal and you should not be alarmed if this happens to you — even if the variations are pretty large.

What time of day is blood pressure the lowest?

Your blood pressure is the lowest when you sleep (for most people, this would be at night). There can still be fluctuations while sleeping, but generally speaking that’s when your blood pressure is lowest.

What time of day is blood pressure the highest?

Blood pressure starts to peak around noon, and is generally most elevated in the afternoon, decreasing before bedtime. Variations can also depend on stress, temperature, physical activity, medicines, and several other factors.

How big can these fluctuations be?

Anecdotally, many people report their blood pressure varying by quite a lot throughout the day. A quantitative analysis from 1991 found that the value for pressure can easily vary by around 20% throughout the day. The variation curves tend to look something like this:

Can these fluctuations affect my tension measurements?

Absolutely. Readings in healthcare settings are typically regarded as the average blood pressure of a person, but that’s not necessarily true. As we’ve seen, blood pressure can fluctuate significantly over the 24-hour-cycle, and also depending on where you measure it.

Some people have what’s known as white-coat hypertension: their blood pressure spikes when they’re in a doctor’s office. Others have “masked hypertension”: the opposite phenomenon, where their pressure is high at home, but drops at the doctor’s.

This is why more and more physicians are recommending regular home monitoring to get a more relevant baseline for a person’s blood tension.

So what’s the best time to measure blood pressure?

There’s no one best time to measure blood pressure. The best practice would be to have it monitored several times a day. A common approach is to measure it twice daily: one time in the morning, before eating or taking medications (but not right after waking up), and the second time in the evening. If you’re having your blood pressure measured at a medical facility, the doctor or nurse can advise you.

Another important tidbit is that loss of the normal fall in blood pressure at night is associated with a greater future risk of cardiovascular disease. There is some evidence that nighttime blood pressure is a stronger predictor than daytime blood pressure, but this is unclear. Blood pressure also varies over longer time periods (months to years) and this variability is useful in predicting adverse outcomes.

Why is my tension high in the morning sometimes?

Blood pressure tends to be relatively low after waking up, but for some people, it can be abnormally high in the mornings. Doctors refer to this as morning hypertension.

People who have morning hypertension may be at risk of cardiovascular problems. A 2010 review notes that stroke and other serious cardiac events are most likely to happen in the first 4–6 hours after waking. However, this could also be caused by other factors such as medication and sleep apnea. You should always consult your physician if you are concerned about morning hypertension.

What’s a ‘good’ blood pressure?

There is an ongoing debate between medical researchers regarding the optimal blood pressure, especially for older people and those taking medicines for hypertension. The general indications typically look something like this:

Observational studies suggest that people who maintain their pressure at the lower end of these ranges have much better long-term cardiovascular health. Regular blood pressure checkups are a must, since hypertension can have severe and long-lasting effects on the body.

What causes high blood pressure

High blood pressure is linked with a number of medical conditions, especially (but not only) cardiovascular diseases. Your genes also affect your risk, but most often, it’s our lifestyle choices that cause high blood pressure. You are at a higher risk of hypertension if you are:

• aged 65 or older;
• overweight or obese;
• smoke;
• drink a lot of alcohol or coffee;
• eat too much salt, meat, and not enough fruits vegetables;
• have a sedentary lifestyle;
• don’t get enough sleep;
• suffer from chronic stress or anxiety;
• are of African or Caribbean descent;
• have a family history of cardiovascular disease.

How to improve your blood pressure

As is so often the case, the best things to do here are healthy lifestyle changes.

• cut down on alcohol and caffeine;
• stop smoking;
• exercise regularly;
• reduce the salt in your diet;
• have a healthy diet with lots of fruits and vegetables;
• work on losing weight if you’re overweight;
• try to get enough sleep and relax adequately;
• get regular health check-ups.