According to a study conducted at West Virginia University, tooth grinding is associated with poor preschool performance.

The study included 1,956 preschoolers, in which 36.8% of preschoolers reported grinding their teeth one or more times per week, and 6.7% reported griding four or more times per week. As the frequency of children’s tooth grinding during sleep increased, parents were more likely to endorse that their child is withdrawn, doesn’t get involved with others, and that preschool adjustment was worse.

"Although we cannot assume that tooth grinding causes withdrawn behaviors or problems in school, the dynamic relation between tooth grinding and preschool adjustment indicate that there may be clinical relevance to tooth grinding beyond being a symptom of bruxism," said Salvatore P. Insana of West Virginia University, author of the study. "Furthermore, parental report of tooth grinding may be a sensitive indicator of the presence of bruxism among young children."

Sleep-related bruxism involves the grinding or clenching of teeth during sleep. It is common for the jaw to contract while you sleep. When these contractions are too strong, they produce the sound of tooth grinding. This can cause dental damage by wearing the teeth down. In most severe cases, hundreds of events can occur during the night. In milder cases, the grinding may vary from night to night.

According to the study, the rate of bruxism seems to be highest in children. About 14% to 17% of children have it. It can begin as soon as a child’s upper and lower teeth have come through the gums. Around one-third of children with bruxism will still have it when they are adults. It also can be caused by stress and anxiety. This may be due to a life event or pressure at school or work.