Sympathetic nervous system is the body’s arousal system (prepares body for action). It forms the basis for fight-or-flight response and is activated by positive experiences. Parasympathetic nervous system is the body’s quiescent system that helps to conserve energy. These systems are antagonistic. Increased activation of one results in decreased activation of the other. (Newberg, Andrew, MD, et al. Why God Won’t Go Away. p 38-40. NY: Ballantine Books, 2001.)