This is true. I suffer from PTSD

 PTSD as a condition that develops after a life-threatening trauma. Victims suffer three types of experiences long afterward, even in a safe environment. They repeatedly re-experience the trauma in nightmares or vivid memories. They avoid situations or feelings that remind them of the event, and they feel keyed up all the time. http://seattletimes.nwsource.com/html/nationworld/2012519877_apusptsdmilitarydogs.html