Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by very stressful, frightening or distressing events.
Sufferers of PTSD will often be forced to relive the event that traumatised them, either through flashbacks or nightmares. Often, they will feel irritable, isolated and guilty, and may have problems sleeping.
The symptoms are often severe and will have an effect on everyday life.
For details on the symptoms and treatments for PTSD, see below.