Grinding of teeth in the night sleep is known as nocturnal teeth grinding, nocturnal teeth grinding serious possible causes are psychological factors, systemic factors, oral and maxillofacial factors, etc., as follows. 1. Psychological factors: the tension and anxiety in daily life may affect the dysfunction of nerves and muscles, and the abnormal excitement of nerves stimulates the contraction of masticatory muscles, which leads to the occurrence of nocturnal teeth grinding. 2. Systemic factors: systemic endocrine disorders may lead to disorders of the nervous system, indirectly affecting the masticatory muscles, leading to nocturnal teeth grinding. 3. Oral and maxillofacial factors: Temporomandibular joint disorders may lead to unstable occlusion of the whole mouth, with early contact or joint interference, which may also lead to the symptoms of nocturnal teeth grinding. There may be other reasons for the severity of nocturnal teeth grinding, so it is recommended to go to the hospital in time.