Stress is a common problem in most societies. There are three main types of stress that may occur in our everyday lives: acute (a brief event such as a heated argument or getting stuck in a traffic jam), acute episodic (frequent acute events such as work deadlines), and chronic stress (persistent events like unemployment from a job loss, physical or mental abuse, substance abuse, or family conflict). Many of us may experience a combination of these three types.
Our bodies react to all types of stress via the same mechanism, which occurs regardless if the stress arises from a real or perceived event. Both acute and chronic stressors cause the “fight-or-flight” response. Hormones are released that instigate several actions within seconds: pumping blood and oxygen quickly to our cells, quickening the heart rate, and increasing mental alertness. In prehistoric times, this rapid response was needed to quickly escape a dangerous situation or fight off a predator. However all types of stress can trigger this response, as described in more detail below:
- A very small region at the base of the brain, called the hypothalamus, sets off the reaction and communicates with the body through the autonomic nervous system (ANS). This system regulates involuntary responses like blood pressure, heart rate, breathing, and digestion. The ANS signals nerves and the hormone corticotropin to alert the adrenal glands, located on the top of each kidney, to release a hormone called adrenaline into the blood. [1]
- Adrenaline (also known as epinephrine) quickens the heart rate and increases blood pressure so more blood circulates to the muscles and heart to support a boost of energy. More oxygen in the blood is available to the heart, lungs, and brain to accommodate faster breathing and heightened alertness. Even one’s vision and hearing may become sharpened.
- If stress continues, the adrenal glands release another hormone called cortisol, which stimulates the release of glucose into the blood and increases the brain’s use of glucose for energy. It also turns off certain systems in the body to allow the body to focus on the stress response. These systems include digestion, reproduction, and growth.
- These hormones do not return to normal levels until the stress passes. If the stress does not pass, the nervous system continues to trigger physical reactions that can eventually lead to inflammation and damage to cells.
With acute stress, the event is brief and hormone levels will gradually return to normal. Acute episodic and chronic stress repeatedly trigger the fight-or-flight response causing a persistent elevation of hormones, leading to a risk of health problems.