Sleeping in late stage of cancer may be caused by malnutrition, brain metastasis of tumor, and some special cancers such as liver cancer, which is caused by hepatic encephalopathy. 1. Malnutrition and other reasons: cancer is a kind of consumptive disease, and patients with advanced stage of cancer may suffer from malnutrition, electrolyte disorder, anemia, etc. Patients with hypoproteinemia caused by malnutrition may suffer from cerebral edema, which may lead to total sleepiness; patients with electrolyte disorder may suffer from total sleepiness due to the decrease of nerve excitability; patients with anemia may suffer from total sleepiness due to the decrease of oxygen supply to the brain. For treatment, patients with malnutrition should strengthen nutrition; patients with electrolyte disorder, such as patients with hyponatremia caused by cancer associated with paraneoplastic syndrome, can be given sodium supplementation; patients with anemia can be given recombinant human erythropoietin or transfusion treatment. 2. Cancer brain metastasis: patients with cancer brain metastasis may also have the symptom of total sleepiness due to the compression of tumor or radiotherapy to the head, treatment can be given mannitol dehydration to reduce the cranial pressure, and treatment can be carried out for brain metastases. 3. Hepatic encephalopathy: hepatic encephalopathy can occur in patients with liver cancer due to liver failure, and patients with hepatic encephalopathy will also have the symptom of total sleep. For treatment, lactulose, rifaximin and other drugs can be used to reduce the concentration of blood ammonia, and protein intake can be restricted, and treatment should be directed at liver cancer.