HPA (Hypothalamic/Pituitary/Adrenal) AXIS 

The hypothalamic–pituitary–adrenal axis (HPA axis or HTPA axis) is a complex set of direct influences and feedback interactions among three components: the hypothalamus, the pituitary gland (a pea-shaped structure located below the thalamus), and the adrenal (also called "suprarenal") glands (small, conical organs on top of the kidneys).

These organs and their interactions constitute the HPA axis, a major neuroendocrine system that controls reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality, and energy storage and expenditure. It is the common mechanism for interactions among glands, hormones, and parts of the midbrain that mediate the general adaptation syndrome (GAS).  While steroid hormones are produced mainly in vertebrates, the physiological role of the HPA axis and corticosteroids in stress response is so fundamental that analogous systems can be found in invertebrates and unicellular organisms as well.

Stress whether positive or negative has the same effect on our nervous system.  Cortisol is released by our adrenal glands in preparation/response.  It is the very thing that keeps us safe, so a very necessary process.  "Cortisol maintains the balance through the unwritten law that “for any physical body to remain in homeostatic equilibrium every inflammatory reaction must have an opposite and equal anti-inflammatory reaction.” Although there are other anti-inflammatory responses occurring at local sites, cortisol is the main anti-inflammatory agent circulating naturally in your body. You can assume that almost any time you have an inappropriate amount of redness and/or swelling, there is too little cortisol in circulation.

Cortisol has similar anti-inflammatory control over auto-immune reactions. In auto-immune reactions, white blood cells attack parts of your body as if they were the enemy. These reactions can range from mild to life threatening. In most auto-immune reactions, cortisol levels are inadequate for the degree of reaction taking place in particular tissues or locations in the body.

Cortisol also reduces the rate at which lymphocytes multiply and accelerates their programmed cell death to further protect the body from this overreaction. In fact, when cortisol is elevated during the alarm reaction, there is almost a complete disappearance of lymphocytes from the blood. That is why your immune system is suppressed when you are under stress or taking corticosteroids. On the other hand, when circulating cortisol is low its moderating effect on immune reactions is lost and lymphocytes circulate in excess. In this situation inflammation is greater with more redness and swelling, and it takes a longer time for the inflamed tissue to return to normal. So, directly and indirectly cortisol dramatically influences most aspects of immune function." more

"Cortisol, is a powerful anti-inflammatory agent. Any acute or chronic inflammatory condition

will signal cortisol release through normal inflammatory signaling and the HPA axis. Undiagnosed inflammation in the GI (IBD, food allergies), chronic inflammatory conditions (joints, cardiovascular) or obesity (central adiposity) will fuel HPA axis dysfunction if not corrected. Furthermore, some pharmacologic agents commonly used to treat the symptoms of chronic inflammatory diseases, such as NSAIDS and opiates, can further exacerbate HPA axis dysfunction"  "The result is amplification of numerous inflammatory pathways and increased susceptibility to developing inflammatory diseases, including autoimmune diseases, mood disorders, atopy,malignancy, chronic fatigue syndrome, chronic pain syndromes, obesity, glucose dysregulation and fibromyalgia. Furthermore, due to down-regulation of humoral immunity, hypocortisol

patients become more vulnerable to assaults by infectious and environmental pathogens such as

parasites, allergens, certain bacteria and toxins." more

"Cortisol is insulin's counterpart. Among many other functions, cortisol takes sugar stored in the liver (glycogen) and puts it into the blood stream. To keep things simple, insulin lowers blood sugar, and cortisol raises blood sugar." more