Post Traumatic Stress Disorder

Post Traumatic Stress Disorder, also known as PTSD, occurs after an individual is exposed to disturbing events outside the realm of human experience.

Prevalence is as high as 60% amongst combat veterans. The individual re-experiences the event through intrusive recollections, nightmares, flashbacks, or intense distress when exposed to reminders of the event. The patient may have feelings of detachment, amnesia, emotional numbing, restricted affect or active avoidance of thoughts that may be reminders of the trauma.

Known occurances
Prior to The Fury's death, in the underground tunnel beneath Groznyj Grad, he began to relive his memories of the disastrous spaceflight mission in which he received his burns, before launching himself into the ceiling with his jetpack.

In 1970, FOX operative Python revealed to Naked Snake that he constantly suffered from nightmares, due to having killed many people, during the "wetworks" missions he undertook for the CIA. Trained as an Anti-Snake Soldier, he believed he could end his nightmares by killing his former comrade. Also, Elisa mentioned to Snake that the memories of the Kyshtym Disaster that killed her parents still haunted her in her dreams. Similarly, at the beginning of the mission, Naked Snake also suffered a nightmare relating to his capture by the FOX unit.

Big Boss was a possible sufferer of PTSD, as he constantly experienced flashbacks to his killing of The Boss, profusely sweating whenever he heard The Boss's voice, or when the Mammal Pod referred to him as "Jack." Also, Militaires Sans Frontières personnel would be sent to Mother Base's sick bay, if they ever began to experience Post Traumatic Stress Disorder. In addition, Paz Ortega Andrade, at least in her act as a schoolgirl, also was implied to have suffered from PTSD as a result of her torture from Hot Coldman at Puerto del Alba.

Ground Zeroes
The sniper team duo Glaz and Palitz ended up self-mutilating their eye and finger, respectively in an attempt to eliminate their past, largely due to the drugs and therapy not being enough to soothe them, implying that they suffered from intense PTSD for their actions during the Laotian Civil War.

Paz, while unconscious when Big Boss rescued her from the Admin Building at the United States Naval Prison Facility in Cuba, often giggled, said "stop it!",  "my stomach, my stomach has", etc,  strongly implying that she was having nightmares relating to XOF's brutal torture on her.

After Operation Intrude N313, Solid Snake began to suffer from recurring nightmares regarding the incident. He undertook Operation Intrude F014, in an attempt to rid himself of them, and after succeeding in his mission, he believed this had come to pass. Big Boss, however, believed that the nightmares could never go away once a soldier has them.

When Snake noticed that Meryl Silverburgh was acting strangely, he contacted Nastasha Romanenko, to which she theorized that she was most likely suffering from the effects of PTSD, as she had a friend who suffered through that same disorder from fighting in Chechnya and taking his own life six months later. Also, in her novel account of the events of the Shadow Moses Incident, In the Darkness of Shadow Moses: The Unofficial Truth, Nastasha speculated that Gray Fox's reactions to Naomi Hunter, as well as his consistently going to the battlefields with Big Boss, were derived from PTSD gained as a child soldier.

Raiden, a former child soldier in the Liberian Civil War, constantly had terrible nightmares relating to his suppressed memories of his involvement as a child, making him fearful of the night. This also serves as the primary reason why Raiden also won't allow people to keep him company in his room, not even Rosemary. In addition, Solid Snake also frequently experienced nightmares relating to the Shadow Moses Incident, including his fight with Liquid on REX, one of his nightmares also being witnessed by Raiden while he was watching Pliskin sleep.

Solid Snake later experienced persistant nightmares of his previous mission to Shadow Moses. Furthermore, Snake theorized that Rat Patrol member Johnny Sasaki suffered from PTSD, and noted that the SOP System should logically counteract its effects. All four members of the Beauty and the Beast Unit (Laughing Octopus, Raging Raven, Crying Wolf, and Screaming Mantis) were also known to suffer from PTSD, being either witnesses and victims to, or participants of, horrible war crimes. Raiden's PTSD also worsened as a result of regaining his memories, which resulted in him heavily drinking, getting into fights, and eventually leaving Rose.

During Raiden's emergency surgery, Raiden frequently flashed back to his days as a child soldier at Liberia. In addition, he also continued to go exclusively by the codename of Raiden due to his real name, Jack, reminding him too much about his painful past as a child soldier. It's also strongly implied that Raiden's PTSD dating back to his actions in Liberia had him develop a murderous split personality called Jack the Ripper.

Soldiers who have experienced PTSD

 * The Fury
 * Big Boss
 * Python
 * Solid Snake
 * Gray Fox
 * Elisa
 * Raiden
 * Laughing Octopus
 * Raging Raven
 * Crying Wolf
 * Screaming Mantis
 * Psycho Mantis
 * Johnny Sasaki
 * Pacifica Ocean

Behind the scenes
Marionette Owl, from the non-canon game Metal Gear: Ghost Babel, claimed that he frequently relived the traumatic event of witnessing Laura's remains strewn across a field after she was murdered by a serial killer in his sleep up to his death.