Parasympathetic Nervous System

A branch of the autonomic nervous system that promotes digestion and procreation when the body is at rest but also serves to counterbalance the effects of the sympathetic nervous system’s fight-flight response and help restore the body to a state of calm after the danger has passed. Triggers decreased heart rate, relaxed breathing, muscle relaxation and release of cortisol and other stress hormones used to dampen the body’s alarm response. Despite the presumption that the universal response to danger entails activation of a state of sympathetic hyperarousal, research by Dr. Jim Hopper and others indicates that approximately one-quarter of humans demonstrate a PSNS-dominant response to trauma characterized by physiological hypoarousal. The PSNS also controls the defensive “freeze” response of the body’s alarm system, characterized by reduced heart rate, motionlessness, hyper-alertness and action-preparation.