Cortisol is often referred to as the stress hormone. Cortisol is actually a hormone that is produced in the adrenal gland, generally in response to either physical or emotional stress. Your body secretes cortisol as part of the body's "flight or fight" response, as a way to help fight off possible stress and danger. As a result, cortisol works to increase the flow of glucose sugars, fat and protein into your blood stream, providing an immediate increase in your energy levels.

Abnormal cortisol levels in the blood stream is an area that is currently receiving a lot of study. Although short-term changes in cortisol levels are normal, certain conditions, medicines and life choices can often lead to abnormal cortisol levels for an extended period of time. Having either too much or too little cortisol in the blood stream can lead to other problems and diseases.