The normal body temperature of human body is between 36-37℃. Long-term hypothermia refers to a body temperature that is higher than normal and lower than 38℃. There are several causes of long-term hypothermia: 1. The most common is infectious fever, such as acute, chronic, systemic and focal infections caused by various bacteria, viruses, mycoplasma and chlamydia. 2. There are also tumors, such as blood diseases, such as lymphoma, leukemia, etc. 3. some allergic reactions and connective tissue diseases, such as rheumatic fever, drug fever, systemic lupus erythematosus, etc., may also cause chronic hypothermia. 4. neurogenic diseases, such as some patients with plant nerve dysfunction, may develop cerebral hemorrhage, etc., and may also cause chronic hypothermia.