Post-traumatic stress disorder (PTSD) is a mental health condition triggered by experiencing or witnessing an incredibly stressful and frightening event. Those with PTSD often experience flashbacks, nightmares, severe anxiety, and depression, and are often unable to control the extent to which they think about the event.    While most people who go through traumatic events experience short-term difficulty coping, those with PTSD experience symptoms that are long-term and that affect their ability to enjoy their day-to-day lives.