Cortisol is the body's primary stress hormone. When the brain stimulates its release in response to physical or emotional stress, the adrenal glands secrete cortisol into the blood. Cortisol helps the body regulate blood sugar levels and blood pressure. It also is an anti-inflammatory, an anti-allergic agent and reduces the actions of the immune system. Many synthetic versions of cortisol, such as hydrocortisone, have medicinal uses.
Studies show cortisol levels are low in many people with fibromyalgia and chronic fatigue syndrome and could be what makes it so difficult to deal with stress, either physical (such as infection or exertion) or psychological. Studies of cortisol replacement, however, have had inconsistent results.
Also see: HPA Axis
