PTSD is an anxiety disorder that can occur after something has happened to make you feel afraid, threatened, or harmed. When this happens, your body responds to the danger by entering a state of alarm, also called “fight or flight.” This increases your heart rate and puts pressure on your muscles and breathing system. Your mind can also react with flashbacks of what’s happened and memories of other frightening events. PTSD damages the neurons in the brain and disrupts communication between them. It can make it difficult to process information clearly and accurately and might interfere with your sleep as well as mental focus. PTSD also affects relationships, as people with PTSD may withdraw from those around them or avoid socializing altogether.