Dizziness when standing up from sitting may be caused by postural hypotension. Patients with postural hypotension generally have lower blood pressure in the sitting position than in the upright position. If you stand up suddenly while sitting and move too violently, it may cause a transient drop in blood pressure, which can easily cause insufficient blood supply to the brain. Insufficient blood supply to the cerebellar brainstem is mainly characterized by dizziness, nausea and vomiting, balance disorder and ataxia, and nystagmus and diplopia may also occur. If the patient has severe hypovolemia, or severe hypotension, sudden standing up from a sitting position may also cause transient cerebral hypoperfusion, which may lead to cerebral hypoperfusion. It can also be seen in people who are physically weak. If the patient has atherosclerosis, the lumen is narrowed, the wall is stiff, and the elasticity of the blood vessels is poor, and when the patient stands up suddenly from a sitting position, it may cause poor vascular regulation, which may lead to cerebral hypoperfusion, causing cerebral blood supply insufficiency.