A perceived challenge can activate the mind/body system, resulting in increased alertness and stronger action, but chronic activation of this response leads to abnormal responses to stress characterized by 1) the inability of the body to return to baseline levels of catecholamines and cortisol, and 2) the inability of the body to activate the biochemical changes associated with a perceived challenge. When either of these response patterns develops due to continual activation of the stress response, then stress becomes debilitating.