Cerebral thrombosis is a common disease in the elderly. Its occurrence is not only related to the progress of hypertension and atherosclerosis, but also closely related to the increase of blood viscosity in the elderly. In fact, the higher the blood viscosity of the elderly, the more likely cerebral thrombosis occurs. Blood flowing in human blood vessels is like a river, the faster the flow, the less precipitation; conversely, the slower the flow, the more precipitation. The higher blood viscosity inevitably leads to slower blood flow, and platelets, cholesterol, fibrin and other substances in the blood will be precipitated on the blood vessel wall, and over time, more and more precipitates will be accumulated, and if combined with hypertension, atherosclerosis and other diseases, it will lead to cerebral thrombosis. Research has confirmed that the viscosity of human blood is constantly changing throughout the day and has its own certain rules: the highest blood viscosity in the morning from 4:00 to 8:00, then gradually decreases to the lowest point in the early morning, and then gradually rises to the peak again in the morning. This regular fluctuation is more prominent in the elderly. In addition, the onset of cerebral thrombosis is mostly in the morning to morning period, which means that the increase of blood viscosity has a certain relationship with the occurrence of cerebral thrombosis. Expert comment: Let the elderly drink 200 ml of commercially available mineral water at night, then the blood viscosity can be reduced in the morning. Reduce blood viscosity, maintain smooth blood flow, and prevent thrombosis. Of course, the cause of cerebral thrombosis is multifaceted, blood viscosity is only one of the many factors, but at least it is certain that the habit of drinking water before bedtime will play a role in preventing the occurrence of cerebral thrombosis.