A sleep-related, stereotyped tooth-grinding movement, common in children and adults. Higher incidence in children with mental retardation, cerebral palsy and adults with significant psychological stress. It can cause tooth wear in about 5% of the general population. Sleep grinding is mainly seen in stage 1 and 2 sleep and REM sleep, and is seen in 85-90% of the general population. In children, teeth grinding is often seen in 5-20% of cases, sometimes up to 10-50%. It can occur in 2-5% and 10-50% of young adults, and in 1-5% and 6-50% of adults and older adults, respectively. The incidence of teeth grinding decreases with age. There is no gender difference in sleep teeth grinding. The etiology of sleep bruxism is unknown. It can be categorized into 3 types: teeth grinding (producing a typical rubbing sound), teeth clenching, and teeth clenching or jaw pulling. The rubbing sound is often detected by co-sleepers as an unpleasant experience, and teeth grinding can lead to abnormal tooth wear, periodontal tissue damage or jaw pain. Sleep grinding is a habitual movement of the mouth, seen as rhythmic activity of the temporomandibular muscles, resulting in obligatory tooth contact during sleep. It is most often accompanied by clenching or grinding of the teeth with a loud sound. Obstructive sleep apnea, severe snorers, moderate daytime sleepiness, severe alcoholism, caffeine consumption, smokers, highly stressful life events, and anxious individuals are at higher risk for sleep grinding. Others such as sleep talking, violent or harmful behavior during sleep, sleep paralysis, and hypnagogic hallucinations are also associated with sleep grinding. There is no effective treatment and dental pads may be tried. Differential Scenarios Rarely, myoclonus of occlusal origin can resemble sleep teeth grinding.