In this clinical summary, the authors explain that sleep bruxism is a nocturnal, orofacial activity. In sleep medicine, it has been described as a parasomnia, associated with simple repetitive movements and transient arousals during sleep. In dentistry, sleep bruxism has been described as a parafunctional activity associated with clenching, bracing, and grinding of the teeth. Because sleep bruxism may provoke destruction of teeth, dental restorations, temporomandibular joint function, and facial pain, dentistry has been more focused on restoring dental work and oral appliances. Although stress has been proposed as a causative factor in aggravating bruxism or being relieved by the bruxism, evidence supports an autonomic imbalance rather than a psychological response. A sequential change from autonomic and brain cortical activities precedes sleep bruxism, suggesting that the central and/or autonomic nervous systems, rather than peripheral sensory factors, have a dominant role in sleep bruxism onset. Also, evidence of underlying genetic links has been proposed. Comorbidities include obstructive sleep apnea, snoring, hypertension, headaches, temporomandibular dysfunction, encephalopathy, epilepsy, affective disorders, psychological stress, and anxiety. At this time, only polysomnographic (PSG) studies can provide a definite diagnosis. Neuroimaging studies provide evidence of functional changes in oral motor cortical areas in patients with bruxism. Treatment of sleep bruxism includes dental orthotics, behavioral modification, medication, and treatment of obstructive sleep apnea.