SNS activation A U.S. Long Range Reconnaissance Patrol leader in Vietnam, 1968. Many of the symptoms initially experienced by<unk>  sufferers are effects of an extended activation of the human body's fight-or-flight response. The fight-or-flight response involves a general sympathetic nervous system discharge in<unk>  to a perceived<unk> or and prepares the body to fight or run from the threat causing the<unk> . Catecholamine hormones, such as adrenaline or noradrenaline, facilitate immediate physical<unk> s associated with a preparation for violent muscular action. Although the flight-or-fight-response normally ends with the removal of the threat, the constant mortal danger in<unk>  zones likewise constantly and acutely<unk> es soldiers. General adaptation syndrome The process whereby the human body responds to extended<unk>  is known as general adaptation syndrome (GAS). After the initial fight-or-flight response, the body becomes more resistant to<unk>  in an attempt to dampen the sympathetic nervous response and return to homeostasis. During this period of resistance, physical and mental symptoms of<unk>  may be drastically reduced as the body attempts to cope with the<unk> . Long<unk>  involvement, however, may keep the body from homeostasis and thereby deplete its resources and render it unable to normally function, sending it into the third stage of GAS: exhaustion. Sympathetic nervous activation remains in the exhaustion phase and<unk> s to<unk>  are markedly sensitized as fight-or-flight symptoms return. If the body remains in a state of<unk> , then such more severe symptoms of<unk>  as cardiovascular and digestive involvement may present themselves. Extended exhaustion can permanently damage the body.
Combat stress reaction
Self-harm
Body substance isolation
Stranger anxiety
Listener fatigue
Automatism 
Derealization
Semantic satiation