Drooling is generally caused by the following factors: First, poor oral hygiene: the temperature and humidity in the mouth are most suitable for the reproduction of bacteria, and the accumulation of food residues or sugar substances on the teeth and tooth surfaces are prone to dental caries and periodontal disease. These undesirable factors have stimulation, which can cause drooling during sleep. Second, the front teeth malformation: this may be due to genetic factors caused by acquired bad habits, such as chewing nails, spitting tongue, biting pencil head, etc., causing the front teeth malformation, sleep drooling. Third, neurological disorders: the regulation of salivary secretion is completely neuroreflexive, the so-called “plum quenching” is an example of conditioned salivary secretion in daily life. So neural regulation disorder, can also produce drooling in bed.