It is possible for blood pressure to decrease when you take a deep breath while taking blood pressure. The increase in pressure in the chest cavity during deep breathing leads to a decrease in venous return blood volume, which can cause a decrease in heart volume, resulting in a decrease in output per beat, which can lower blood pressure. In addition, deep breathing can slow down the heart rate by stimulating the vagus nervous system, which may also affect blood pressure and lower it. During the measurement of blood pressure, it is not recommended to breathe too deeply in amplitude to avoid the corresponding effect on blood pressure. It is recommended to avoid strong tea, alcohol and coffee-based stimulating beverages 30 minutes prior to blood pressure measurement and to sit quietly in a seat with a backrest five minutes prior to measurement. It is recommended to monitor blood pressure three times when measuring blood pressure and take the average of the last two blood pressure measurements as the value for this measurement.