Grinding or clenching your teeth is known as Bruxism. You may be unaware if you are clenching during the day or grinding and clenching during the night. Occasional teeth grinding doesn't cause harm, but if teeth grinding occurs on a regular basis and has been going on for a long time, it will cause damage and wear on the teeth causing other oral health problems. But why do people grind their teeth? Some reasons may be due to anxiety and stress, an abnormal bite or crooked teeth and by a sleep disorder or sleep apnea.