Sleeping and biting cheek flesh may be caused by diseases such as bruxism and sleep-type epilepsy. 1. Teething disorder: the causes of this disease include heredity, mental stress, abnormal function of the central nervous system, dental occlusion disorders, gastrointestinal dysfunction, etc. It usually manifests itself as grinding or clenching of teeth in the nighttime sleep, so some patients may experience cheek biting in their sleep. 2. Sleep-type epilepsy: This disease belongs to a common seizure classification of epileptic seizures, and studies have shown that it may be related to heredity, brain injury, brain tumors, cortical developmental disorders, central nervous system infections, parasitic infections, and inherited metabolic diseases. When the patient has a nocturnal attack he or she will experience muscle twitching at the corners of the mouth, biting the flesh of the cheeks, generalized muscle tonus, dilated pupils, and chewing. All in all, there are many causes of cheek biting in sleep, patients need to go to the hospital in time, complete a series of related examinations, and cooperate with the doctor for active treatment after clarifying the specific causes.