Post Traumatic Stress Disorder is a disorder which may develop following exposure to anyone of a variety of traumatic events that involve actual or threatened death, or serious injury.

The event may be witnessed rather than directly experienced, and even learning about it may be sufficient if the persons involved are family members or close friends. Sufferers may experience flashbacks, night terrors and heightened awareness. PTSD is sometimes found in ex-military personnel who have been involved in conflict situations, road traffic accidents and with other trauma(s).