Any action that you perform with your mouth that is not related to eating, drinking, or speaking is considered a parafunction. Parafunctional can be bad habits like biting your fingernails or something involuntary like clenching your jaw at night. Whether your para functions are conscious or unconscious, it's essential to try and break these bad habits as they can cause damage to your teeth and temporomandibular joint (TMJ). Bad habits to break are – biting your fingernails, chewing on a pen or pencil, sleeping on your stomach, eating hard or chewy foods, and using your teeth as a tool (like opening packages, plastic, or glass bottles).