Teeth grinding, also known as bruxism, is when a person clenches their jaw and the upper and lower teeth scrape and grind against each other. Most people who grind their teeth do so while sleeping, but some also grind their teeth during the day as a subconscious habit. What Causes Teeth Grinding? There is no one known cause of bruxism, but it is believed that a combination of physical, psychological and genetic factors may be to blame. While teeth grinding during the day may be caused by emotions like anxiety or stress, teeth grinding at night may be caused by a number of different reasons: Sleep disorder Sleep-related chewing motions in between dream states An abnormal bite – your upper and lower teeth may overlap or otherwise …