Drowsiness can be caused by high blood pressure, cerebral arteriosclerosis or neurasthenia. 1. High blood pressure: If the blood pressure fluctuates excessively, the phenomenon of fluctuation and elevation, resulting in an increase in cerebral blood perfusion, can also cause dizziness. 2. 2. Cerebral arteriosclerosis: the thickening of blood vessel walls, narrowing of the lumen, resulting in slowing down the speed of blood flow, so that the brain localized lack of oxygen, but also make the patient’s head drowsy. 3. Neurasthenia: a psychological disease that is mainly characterized by the weakening of brain and body functions under long-term tension and stress. The main manifestations are weakened mental activity, easy to fatigue, difficult to concentrate. Often accompanied by emotional irritability, worry. Nervousness, sleep disorders and other manifestations, the patient will show a heavy head dizziness. Dizziness may also be caused by other diseases, it is recommended that patients should go to the hospital in time to clarify the cause of the disease, under the guidance of the doctor reasonable treatment.