A key aspect of a healthy adaptational response to stress is the time course. Responses must be initiated rapidly, maintained for a proper amount of time, and then turned off to ensure an optimal result. An over-response to stress or the failure to shut off a stress response can have negative biological consequences for an individual. Healthy human responses to stress involve three components:

The brain handles (mediates) the immediate response. This response signals the adrenal medulla to release epinephrine and norepinephrine. The hypothalamus (a central area in the brain) and the pituitary gland initiate (trigger) the slower maintenance response by signaling the adrenal cortex to release cortisol and other hormones. Many neural (nerve) circuits are involved in the behavioral response. This response increases arousal, focuses attention, inhibits feeding and reproductive behavior, reduces pain perception, and redirects behavior.

The combined results of these three components of the stress response maintain the internal balance (homeostasis), increase energy production and utilization, and alter electrolyte (chemical elements) and fluid balance in the body. They also gear up the organism for a quick reaction through the sympathetic nervous system (SNS). The SNS operates by increasing the heart rate, increasing blood pressure, redirecting blood flow to the heart, muscles, and brain and away from the gastrointestinal tract, and releasing fuel to help fight or flee the danger.