Blood pressure in an individual is not constant but varies during the day depending on different factors :
- It decreases at rest and increases with physical activity.
- It falls when asleep.
- It increases with meals.
- It varies with the ambient temperature.
- A strong emotion causes a significant increase (systolic pressure can reach 200 mmHg in a perfectly normal subject).
Knowing this, there are some precautions of use to observe before and during measurement:
- Take your measurements under the same conditions (at the same time of day, on the same arm).
- Relax for 5 minutes before taking a measurement.
- Sit comfortably in a quiet place, feet flat on the floor, without crossing your legs.
- Place the cuff at the same level as your heart. See How to place the cuff properly.
- Don't talk and don't move for the entire measurement.
- Breathe normally.