It is characterized by intrusive reminders of the event such as nightmares and flashbacks, avoidance of stimuli associated with the event, persistent negative cognitions and numbing of responses, and symptoms of anxiety, including hyper-vigilance, difficulty concentrating, irritability, and sleep disturbances. PTSD is associated with substantial distress and impairment in functioning. (Rowe, Sperlich, Cameron, and Seng para. 8, 2014)