Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by very stressful, frightening or distressing events.Someone with PTSD will often relive the traumatic event through nightmares and flashbacks, and may experience feelings of isolation, irritability and guilt. They may also have problems sleeping, such as insomnia, and find concentrating difficult. These symptoms are often severe and persistent enough to have a significant impact on the personÂ’s day-to-day life.Symptoms of PTSD often are grouped into three main categories, including Reliving, Avoiding,Increased arousal etc.Most people associate PTSD with battle-scarred soldiers and military combat but any overwhelming life experience can trigger PTSD, especially if the event feels unpredictable and uncontrollable.