What time to measure blood pressure so that it is reliable
Measuring your blood pressure is not a trivial action. For the results to be useful, you must know how to choose the right times of day, those where natural variations are most marked. This is the key to getting a true picture of actual voltage, not just meaningless point values.
The specialists’ recommendations are clear: two moments are to be favored for an effective domestic measure. In the morning, ideally within an hour of waking up, even before having a coffee, a cigarette or your antihypertensive treatment. Then in the evening, at the end of the day, preferably before dinner or at least two hours after the last meal. Each time, it is advisable to take three measurements spaced one to two minutes apart.
The goal of blood pressure control is not only to achieve normal values from time to time, but to ensure that the pressure remains stable and within the limits set by the doctor throughout the day and night.
These times are not chosen at random.
- In the morning, blood pressure experiences a sudden surge known as the “morning peak”, which is directly associated with a higher risk of stroke or heart attack;
- Conversely, during the night, blood pressure naturally drops. When this phenomenon does not occur, we speak of a “non-dipper” profile, an indicator of poorer cardiovascular prognosis.
The conditions for a truly representative measurement
Time isn’t everything. A reliable measurement also relies on strict conditions to be respected each time. Before taking your blood pressure, you must have been sitting for at least five minutes, with your back supported, your feet flat, without having smoked, drunk coffee or made any physical effort in the previous 30 minutes. According to Health Insurance, the ideal procedure is as follows:
- Sit comfortably in a chair, making sure your back is firmly against the backrest. Keep your legs uncrossed and place your feet flat on the floor.
- Place your exposed arm on a table, so that the middle of the arm is at heart level.
- Wrap the cuff around your bare arm, following the device’s instructions. Start the device: the cuff will inflate then deflate automatically. During the measurement, remain still, do not speak or make a fist.
- The blood pressure monitor screen will display two values in millimeters of mercury (mm Hg). The first, highest number represents systolic blood pressure, measured when the heart contracts to push blood through the arteries. The second number indicates diastolic blood pressure, measured when the heart is relaxed and filling with blood.
- Note these values carefully on a self-measurement blood pressure reading.
- Send the 18 measurements taken over 3 days to your doctor so that he can calculate the average.
Health Insurance offers online self-measurement blood pressure readings.
The High Authority of Health even recommends measuring blood pressure outside the doctor’s office, at home (to avoid the “white coat effect”) by taking 3 measurements in the morning before breakfast and taking medication, 3 measurements before bedtime, 3 days in a row (“rule of 3”), spacing the measurements a few minutes apart.
Frequency, duration, mistakes to avoid: what doctors recommend
As a general rule, to diagnose high blood pressure (hypertension) and before each medical appointment, it is recommended to measure your blood pressure for 3 to 7 days.
If you are receiving treatment for hypertension, your doctor will advise you to check your blood pressure regularly, usually once or twice a week.
Here are the reference values at home:
- Normal blood pressure: below 140/90 mmHg
- Normal average at home: below 135/85 mmHg
- Hypertension at home: equal to or greater than 135/85 mmHg (averaged over several days)
Apart from these regular measurements, additional checks may be required, particularly in the event of unstable blood pressure, suspicious symptoms or to assess the nocturnal effectiveness of the treatment using an ambulatory blood pressure monitor (ABPM).
Certain particular profiles require adjustments: pregnant women, night workers, elderly people, or patients suffering from arrhythmias such as atrial fibrillation. Finally, in all cases, the morning measurement should be done before taking the medication to assess 24-hour coverage, and sometimes a post-medication measurement is requested to assess the peak effect.
The most common errors are, however, easy to avoid: not relying on a single value, not changing the time each day, not using an unsuitable device or incorrectly positioning the cuff. Another mistake: only measure your blood pressure when you don’t feel well – this is the best way to completely bias the results.
| Time of day | When to measure | Why it matters | Precautions to follow |
|---|---|---|---|
| Morning | Within an hour of waking up Before breakfast, coffee, cigarettes and medications |
Evaluate the nighttime effectiveness of the treatment Identify the morning peak of tension |
5 min rest No effort or incentive Measurement before any activity |
| Evening | At the end of the day Ideally before dinner or 2 hours after the meal |
Detect possible peaks linked to stress or fatigue | Avoid recent meals Be relaxed and sit calmly |
| Other times | According to the doctor’s request Particularly 2 hours after taking the treatment |
Efficiency control at its peak Assessment of atypical profiles |
Follow the standard instructions Do not multiply unnecessary measures |