The difference in blood pressure between sitting and lying down may be caused by different body positions. The difference in blood pressure between sitting and lying is due to the fact that the amount of blood in the heart decreases when sitting, causing the body’s sympathetic endocrine system to over-activate, leading to an increase in the body’s adrenaline secretion, peripheral vasoconstriction, and then an increase in blood pressure. Clinically, it is mainly seen in patients with postural hypertension. Whether lying or sitting, the sphygmomanometer should be at the same level as the heart to ensure consistency in measuring blood pressure. In addition, the position of the arm should be measured at a distance between about two horizontal fingers above the level of the elbow, and the elasticity should extend to one finger. However, the measurement of the general gap will not exceed 10 mmHg, the current measurement of blood pressure are lying down, so that the measurement will be more standard, try not to eat stimulating food before the measurement of blood pressure, to avoid affecting the normal measurement results. So in the measurement of blood pressure, whether sitting or lying, should be fully rested after 15 minutes, and then the sphygmomanometer and the heart to maintain the level, so that the measured value is more accurate.