If the legs occasionally appear when sleeping for up is not a big problem, if often appear when sleeping legs arch up, because of the following kinds of pathological response: First, sleep real phase deficiency, usually deep sleep phase deficiency, shallow sleep phase too much, appear in the nervous system dysfunction, plant nerve dysfunction caused by insomnia or sleep insomnia, etc., will appear when sleeping legs often arch up. Second, the sequelae of cerebrovascular disease, the sequelae of previous stroke, cerebral hemorrhage, cerebral infarction, cerebral infarction sequelae, etc., will appear involuntary neurological excitation when sleeping, such as abnormal discharge of brain neurons will appear when the legs often arch up, or appear involuntary leg touching, twitching, etc. Third, in the sequelae of epilepsy or abnormal discharge of brain neurotransmitters, such as Parkinson’s disease will also appear in the legs for up during sleep.