While the etiology of nocturnal bruxism is unknown, three major categories of theories have been advanced to explain its cause(s), i.e., local-mechanical theories, psychological theories and systemic/neurophysiological theories. The recent report of a four-fold increase in the incidence of self-reported nocturnal bruxism in college students over the last 23-year period emphasizes the role that psychological variables may play in the development of this disorder and it is suggested that the personality traits which contribute to stress management are primary among these.