When young people suddenly stand up and faint, it may be related to postural hypotension, or it may be caused by hypoglycemia and transient ischemic attack. 1. Postural hypotension: if young people suddenly get up after being in a squatting position for a long time, the blood in the whole body can not be redistributed in time due to the rapid and violent speed of getting up, resulting in insufficient perfusion to the brain, which can easily induce postural hypotension and may show fainting when they suddenly stand up. 2. Hypoglycemia: some young people may suffer from hypoglycemia due to long-term irregular eating or long-term dieting to lose weight. When hypoglycemia occurs, the brain cannot get sufficient energy supply, resulting in ischemia and hypoxia of brain tissues, which may lead to sudden fainting, accompanied by symptoms such as panic and excessive sweating. 3. Transient ischemic attack: some young people suffer from high blood pressure, diabetes and other pathologies, resulting in transient ischemic attack, may suddenly stand up and faint, may also be accompanied by sudden numbness on one side of the body, weakness, sudden vision loss and other symptoms. If a young person suddenly stands up and faints, and if it occurs frequently and repeatedly, he or she should consult a doctor as soon as possible, and after a clear diagnosis of the causative factors, the treatment should be guided by a doctor.