A healthy relaxed person is in homeostasis, that is, the body is physiologically and psychologically in a state of balance. When stressed, the body produces adrenalin, cortisol, and other strong chemicals in response, whether the perceived or experienced stress is psychological or physical. The body is well prepared to utilize these powerful chemicals by focusing on attention, dampening perceptions to distractions, limiting the ability to feel pain, or providing powerful boosts to available energy.

When a person is stressed over a long period, though, these substances can cause serious negative impacts on his or her health, including: sleep disruption, chronic headaches, hormone disruption, gastrointestinal distress, weight gain, immune system impairment, cardiovascular impacts, and psychological disturbances.

In the short term, stress challenges the immune system, adjusts blood pressure, increases heart rate, shifts neurotransmitters, and regulates the central nervous system. In the long term, stress damages the body's systems, reduces its ability to cope with disease, and impairs brain function and mental health.