Hormones in the human body are delicately balanced by the actions of different glands. The master gland of the human body is the pituitary gland in the base of the brain, and the hormones it releases control the function of other glands throughout the body (hence the term "master gland"). The pituitary gland releases a hormone called ACTH which stimulates the adrenal glands, located atop each kidney, to produce cortisol. Cortisol helps the body deal with stress by regulating immune function, blood glucose (sugar) levels and blood pressure. An imbalance in the production of cortisol may lead to several conditions, each with their own set of signs and symptoms.
If cortisol is too high, it will trigger the release of higher-than-normal levels of glucose into the blood stream. This increased blood glucose causes symptoms similar to those seen in people with type 2 diabetes, including fatigue. This is because the glucose in the blood does not necessarily mean that it is available as fuel for the muscles and other organs.
Cortisol decreases the function of the immune system as a response to stress. In fact, a cortisol-like medication called prednisone is used to treat autoimmune disorders like rheumatism. People with excess levels of cortisol in their body will have immune systems that have virtually shut down, leading to frequent infections, especially bacterial infections.
Dizziness and Fainting
Low levels of cortisol lead to a decrease in blood pressure. When the body's blood pressure goes down below normal levels, the blood is not able to reach the brain as efficiently, leading to a sense of dizziness and maybe even fainting.