Notice the difference between a relaxed brain and a stressed one.Stress is how the body react to challenges or stressors. Stress is a medical term for a wide range of strong external stimuli, both physiological and psychological, which can cause a physiological response called the general adaptation syndrome.Stress activates the sympathetic branch of the autonomous nervous system and the release of stress hormones including epinephrine, and cortisol. Sympathetic nervous output produces the fight-or-flight response, causing the body to divert the normal bloodflow. Less blood flows to the digestive system and other organs that do not assist in the stress condition, producing dry mouth, motor agitation, sweating, pallor, enlarged pupils and over the long term, insomnia. Stress is overcomed when the parasympathetic branch gets activated reversing the effects of sympathetic nervous system.