Cortisol and Your Body’s Stress Response
No matter what the source of stress, most challenges to homeostasis stimulate the HPA axis (hypothalamus, pituitary and adrenal glands), resulting in increased secretion of cortisol. In animal experiments, those with weakened adrenals died in response to even mild stress. However, when animals with weakened adrenals were given cortisol or similar agents, they survived those same kinds of stress. People with a weakened stress response can often tolerate mild stress, but succumb to severe stress. As stress increases, progressively higher levels of cortisol are required. When these higher levels of cortisol cannot be produced, the person cannot fully or appropriately respond to stress, leading to conditions like adrenal fatigue.
Even at normal levels, cortisol serves the very important function of priming the different mechanisms of your body so they can respond when called into action. During stress, cortisol must simultaneously provide more blood glucose, mobilize fats and proteins for a back-up supply of glucose, and modify immune reactions, heartbeat, blood pressure, brain alertness and nervous system responsiveness. Without cortisol, these mechanisms cannot react adequately to a significant stress. When cortisol levels cannot rise in response to these needs, maintaining your body under stress is nearly impossible. The more extreme the difference between the level of stress and the lack of cortisol, the more significant the consequences.
Cortisol can be viewed as sustaining life through two opposite but related kinds of regulatory actions: releasing and activating existing defense mechanisms of the body and shutting down and modifying the same mechanisms to prevent them from overshooting and causing damage or cell death. If this regulation is defective during stress, as it is when cortisol levels are low, an animal can be endangered or even die because its defense mechanisms cannot react or because they overreact.
When your body is stressed, cortisol is also needed to restrain various physiological mechanisms to prevent them from damaging your body. For example, the elevation of blood sugar by the adrenals during stress helps control the insulin-induced hypoglycemia that would occur if more blood glucose was not available. But cortisol also protects the cells against the detrimental effects of excessive amounts of glucose by helping create insulin resistance at the cell membrane to keep too much glucose from flooding into the cell.
This damping down action of cortisol can also be seen in the way cortisol modifies the immune response to control the amount of inflammation in the involved tissues and suppress potentially toxic chemicals secreted by white blood cells, thus protecting the body from auto-immune processes and uncontrolled inflammation.
Cortisol is so important that when the HPA axis cannot increase cortisol activity in response to stress, these unrestrained mechanisms overshoot and can damage your body. In summary, these actions of cortisol have evolved to both enhance the body’s response to stress, yet protect it from excessive responses to stress. These mechanisms were probably needed only occasionally in our distant ancestors’ lives. However in modern life, with the myriad of physical, emotional and environmental stresses we face daily, our adrenals’ capacity to rise to the occasion is challenged day after day. It is possible that we experience more stressful events in a year than our ancestors experienced in a lifetime. Yet your adrenal glands require some recovery time each time they are challenged.
The constant “pedal to the metal” lifestyle leaves little room for an adequate adrenal response when the adrenal glands never get the chance to recoup and are already responding at their maximum capacity. The more we understand about the physiology of stress, the more obvious it is that, unless we quickly evolve to have adrenal glands the size of footballs, we must learn to give our adrenals the opportunity they need to recover on a regular basis. This means modifying the effects that stress is having on your body. Otherwise, we will rapidly devolve into a society of the chronically sick and tired that even coffee, colas and other stimulants cannot keep going.
Image Credits: man pulling his hair by Flickr user stuartpilbrow
About the Author:
With a researcher’s grasp of science and a clinician’s understanding of its human impact, Dr. Wilson has helped many physicians understand the physiology behind and treatment of various health conditions. He is acknowledged as an expert on alternative medicine, especially in the area of stress and adrenal function. Dr. Wilson is a respected and sought after lecturer and consultant in the medical and alternative healthcare communities in the United States and abroad. His popular book Adrenal Fatigue: The 21st Century Stress Syndrome has been received enthusiastically by physicians and the public alike, and has sold over 400,000 copies. Dr. Wilson resides with his family in sunny Tucson, Arizona.