"The human body produces its own heroin. In fact, when the fight-or-flight instinct is activated in the hypothalamus, your body releases endorphins, dopamine and norepinephrine. That is heroin, cocaine and amphetamine, all at once... There is a reason to believe that a person can get addicted to this type of high."
Fahim Ahmadzai - Whiskey Tango Foxtrot
http://www.imdb.com/title/tt3553442/quotes?item=qt2958783