There are many causes of lethargy, the common causes are mainly the following: first, cerebrovascular disease, such as cerebral hemorrhage, large cerebral infarction and other diseases, can cause ischemic necrosis of brain tissue, brain dysfunction, resulting in lethargy, serious cases will also appear coma, brain death, etc., need to improve the head examination to clarify the specific cause. Second, epilepsy, the disease is due to abnormal discharge of neurons, such as frequent seizures can cause brain function impairment and drowsiness, according to clinical performance and EEG examination can be clearly diagnosed, need to take regular anti-epileptic drugs such as carbamazepine, phenobarbital, etc. to control seizures. The third, intracranial infection, the disease is due to viruses, bacteria, fungi and other microbial infestation caused by brain tissue infection, can appear severe headache, serious cases will cause coma, coma and other situations, improve the cerebrospinal fluid examination can clarify the specific cause of treatment.