There are many causes of bruxism, including: Lifestyle habits, such as drinking alcohol, using cigarettes and recreational drugs, and consuming a lot of caffeine (more than six cups of coffee a day). People who drink and smoke are twice as likely to grind their teeth as people who don’t. Sleep disorders. Stress and anxiety. Taking certain medications, including a class of anti-anxiety drugs called selective serotonin reuptake inhibitors (SSRIs).