Blood pressure lying down is normal, and sitting down is commonly associated with irregular blood pressure measurement and upright hypertension.
1. Unstandardized blood pressure measurement: when measuring blood pressure while sitting, you should keep the sphygmomanometer and arm at the same level, with the upper limbs extended and the palms of the hands curled up naturally. If the measurement is not standardized or if you exercise strenuously before the measurement, it will lead to high blood pressure while lying down and high blood pressure while sitting and you need to take an average after several times of blood pressure measurement.
2. Upright hypertension: It means that the blood pressure is normal when lying down, but high when standing up. It belongs to the early stage of primary hypertension, commonly seen in young people, and is related to small artery spasm. Generally, it does not need special treatment, and can be adjusted by adjusting lifestyle and enhancing exercise.
If the blood pressure is normal when lying down but high when sitting, accompanied by some nausea and vomiting as well as dizziness and headache, you should go to the hospital immediately.