If a patient has dizziness and nausea after prolonged head-down, the following factors should be taken into consideration: 1. When the posterior circulation ischemic, dizziness, accompanied by nausea and vomiting, will occur after prolonged head-down. 2. If the patient has definite hyperlipidemia or high blood viscosity, dizziness accompanied by nausea will also occur after prolonged head-down. 3. If the patient has obvious cervical spondylosis, especially in the 2nd-7th cervical spine disc protrusion or bulge, the patient will have dizziness and nausea after prolonged head down, which will lead to compression of blood vessels and nerves. 4. If the patient with hypertension has prolonged head down, blood pressure regulation dysfunction and blood pressure fluctuation will occur, which will also lead to dizziness and nausea.