1. There are parasites in the intestines, especially ascaris lumbricoides, which survive by absorbing nutrients from the human body. It moves in people's stomachs, which not only causes stomach pain, nausea and vomiting, but also causes intestinal obstruction in severe cases, and sometimes makes people grind their teeth at night.

Second, children are too tired or too excited during the day, especially when they play too tired. After falling asleep, the cerebral cortex is not completely rested, and some nerves are still excited, and they will grind their teeth after falling asleep.

Third, the stomach is indigestion, and the digestive function of the stomach can't digest food effectively for some reasons, such as gastropathy, so that the teeth grind after sleeping.