The following are the main possibilities: 1, the patient is nervous, very anxious, by repeatedly swallowing saliva to relieve discomfort, has become a habit, like to reduce pressure by swallowing saliva when sleeping. 2, the patient has oral secretion gland diseases, such as inflammatory diseases of the submandibular gland, parotid gland and other glands, resulting in gland secretion is very strong, easy to appear a lot of saliva, especially at night when sleeping, saliva The patient has chronic laryngitis, repeated inflammatory stimulation of the throat, lymphatic follicle hyperplasia at the root of the tongue at the back of the pharyngeal wall, resulting in a lot of secretions, leading to non-stop salivation and phlegm in the throat. 4, the patient has reflux pharyngitis, gastric juice from the stomach and esophagus keeps refluxing into the throat, stimulating the mucous membrane of the throat, resulting in inflammatory reactions, leading to non-stop salivation of the patient.