Bruxism is a disease thought to be mainly psychological in origin although some pathology of the nervous system cannot be ruled out. It is characterized by the grinding of the teeth, or the making of clicking sounds, or kinds of gnashing. Less obviously, teeth clenching and other voluntary or involuntary movements of the lower jaw muscles may be exhibited. The movements can occur around the clock and unconscious teeth grinding by children and adults while sleeping is well-known. Bruxism wears the teeth and bones supporting them and is a factor in peridontal disease. Bruxism in mild forms may be very prevalent in high-stress societies.