Recent research concluded that neither occlusal interference nor factors related to the oral facial skeleton have a role in the aetiology of bruxism. Recent studies suggest that sleep bruxism is secondary to sleep related arousals (defined by a rise in autonomic cardiac and respiratory activity that tends to be repeated 8-14 times per hour of sleep). The rhythmic muscle activity that occurs in sleep bruxism peaks in the minutes before rapid eye movement sleep. This suggests that there is some mechanism related to sleep stage transitions that influence the motor neurons of bruxism.