Bruxism during the day. The ICDS-R defined sleep bruxism as "a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep", classifying it as a parasomnia. The second edition (ICSD-2) however reclassified bruxism to a "sleep related movement disorder" rather than a parasomnia. Alternatively, bruxism can be divided into "primary bruxism" (also termed "idiopathic bruxism"), where the disorder is not related to any other medical condition, or "secondary bruxism", where the disorder is associated with other medical conditions. Secondary bruxism includes iatrogenic causes, such as the side effect of prescribed medications. Another source divides the causes of bruxism
Bruxism then observed high levels of bruxism-like muscular activity in rats that were allowed to watch this treatment compared to rats that did not see it. They proposed that the rats who witnessed the electrical shocking of other rats were under emotional stress which may have caused the bruxism-like behavior. Some research suggests that there may be a degree of inherited susceptibility to develop sleep bruxism. 21–50% of people with sleep bruxism have a direct family member who had sleep bruxism during childhood, suggesting that there are genetic factors involved, although no genetic markers have yet been identified. Offspring of people