A behavioral or psychological symptom that typically occurs following exposure to one or more traumatic events is posttraumatic stress disorder (PTSD). Symptoms of PTSD include intrusive recollections, such as re-experiencing the trauma through flashbacks, memories, or nightmares. Additionally, individuals may experience avoidant and numbing symptoms, which can include diminished emotions and avoidance of situations that serve as reminders of the traumatic event. Hyperarousal is another symptom, characterized by increased irritability, exaggerated startle reactions, and difficulties with sleeping or concentrating. [from
HPO]