Sleeping always drooling may be related to oral diseases, infant teething, neurological disorders, improper sleeping posture and other factors, need to be specifically analyzed. 1. Oral diseases: some diseases will stimulate the secretion of salivary glands, such as stomatitis, periodontitis, tonsillitis, etc. Excessive secretion of saliva may cause drooling during sleep. 2. Infantile teething: infants can not swallow saliva in time, resulting in frequent salivation, mostly seen in the teething period, with age will gradually improve. 3. Neurological diseases: such as Parkinson’s disease, facial nerve palsy, etc., can have drooling performance. 4. Improper sleeping position: when lying on the side, the face is compressed, and the symptoms of drooling are easy to appear. If drooling occurs frequently during sleep and is accompanied by other symptoms, it is recommended to consult a doctor in a timely manner to clarify the cause of the disease, so as not to delay the condition.