1. Poor oral hygiene: the temperature and humidity in the oral cavity are most suitable for the reproduction of bacteria, and food residues or sugar substances accumulate between the teeth and the tooth surface, which is prone to dental caries and periodontal disease. These bad factors are very irritating, and you will drool when you sleep.

2. Anterior tooth deformity: This may be due to acquired bad habits caused by genetic factors, such as biting nails, sticking out tongue and biting pencils. , causing deformity of the front teeth and drooling when sleeping.

3. Neuroregulatory disorder: the regulation of saliva secretion is completely reflective. The so-called "looking at plum to quench thirst" is an example of conditioned reflex saliva secretion in daily life. If the child still drools after 2-3 years old, he can go to the hospital to ask a pediatrician for examination, do a professional examination, check the functions of nerves, brain, swallowing and muscles, and treat them in time.