Trauma can follow an event that causes extremely high levels of stress such as living through a natural disaster, witnessing a violent incident, or being involved in a car accident. But gradually, the stress of the trauma will ease as your nervous system returns to normal. With PTSD, however, your nervous system doesn’t return to normal following the traumatic event. Your mind and body seem “stuck” in that moment of past trauma and your symptoms affect your ability to function on a daily basis.