Is a little stress good for you?

The Body Under Stress: Danger, Will Robinson!

Stress is one or more outside forces exerting physical or psychological pressure on a person. When the body detects stress, it responds with the stress response. The stress response can be produced not only by negative events, but by positive events as well. When presented with a certain level of stimulation (which varies for everyone), our bodies release hormones that ramp up our metabolism. This occurs when chemical signals are sent from the brain's hypothalamus to the pituitary gland to the adrenal cortex. The end result is the release of steroids such as cortisol and adrenaline.

Cortisol affects you in many ways: It improves your ability to process and use sugars, it allows for faster repair of tissue damage and it shuts down the processes of your body deemed unnecessary at that time, such as growth and digestion.

Adrenaline gets your body ready for action: Your heart pounds and your blood pressure increases because your heart is contracting harder. Your lungs open up, the bronchioles expanding in preparation to meet the demands for more oxygen. You begin to sweat. You become hyperfocused, viewing the world almost literally with tunnel vision as your peripheral vision diminishes. You're ready to face that mountain lion -- or to ask for that raise.

When the excitement fades, so do your elevated levels of cortisol and adrenaline. However, when you perceive different sources of stress all around you -- be it finances, career, marriage or traffic -- your stress response never fully turns off, and the long-term presence of those stress hormones begins to wreak havoc on your body. With stress hormones present, your body processes sugar quickly, and when it runs out of sugar, tissue and muscle damage occur. Over time, constant stress can lead to heart disease, digestive issues, depression, bone loss and sleep disorders. The immune system gets a short-term boost from a stress response, but after a few minutes it goes downhill as the number of cells tasked with fighting infection, tumors and viruses decreases [source: American Psychological Association].

So how could stress possibly be good for you? Keep reading to find out.