Somnolence means that the patient shows alterations in his consciousness that cause increased sleep, but after gently stimulating the patient, such as calling the patient or lightly touching him, the patient opens his eyes and can correctly answer the questions asked or can complete the instructions given to him. Altered consciousness can be classified from mild to severe as drowsiness, lethargy, and coma, with increasing degrees of altered consciousness in that order. A normal person’s consciousness should be lucid and in good mental condition. The clinical causes of drowsiness, lethargy and coma are mainly ischemia and hypoxia in the brain, such as cerebral infarction, cerebral hemorrhage, carbon monoxide poisoning, etc.