Acute Stress Disorder (ASD) is characterized by dissociative symptoms (e.g. detachment, derealization, or amnesia) during or after exposure to a traumatic event followed promptly by symptoms of re-experiencing, avoidance/ numbing, and hyperarousal from two days to a maximum of four weeks after the traumatic exposure. While not the only disorder seen acutely after exposure to traumatic events, ASD is quite common.