Stress is how the body reacts to a real or imagined stressor — a stimulus that causes stress. Acute stressors affect a bodily organ in the short term; chronic stressors over the longer term. Chronic stress is the state of prolonged tension from internal or external stressors which may cause various physical manifestations such as asthma, back pain, arrhythmias, fatigue, headaches, irritable bowel syndrome, ulcers, and suppression of the immune system. Chronic stress takes a more significant toll on the body than acute stress. It can raise blood pressure, increase the risk of heart attack and stroke, and induce symptoms of anxiety and depression.

 The Three Stages of Stress – From Acute to Chronic

• Alarm:  In this first stage, when the threat or stressor is first identified or realized, the body’s stress response is in a state of alarm. During this stage, adrenaline is produced in order to bring about the flight-or-fight response, causing sweating, raised heart rate, etc. The body’s resistance to the stressor drops temporarily below the normal range and some level of shock may be experienced. There is also some activation of the HPA Axis, producing cortisol, as discussed in our last post.

• Resistance:  If the stressor persists, the body must find some means of coping with the stress. Although it begins to try to adapt to the strains or demands of the environment, the body cannot keep this up indefinitely, so its resources are gradually depleted.  As it attempts to cope with the condition that is causing the stress, the mind may try to focus on the problem, which can actually exaggerate the awareness of the problem and make it seem difficult to overcome.

• Exhaustion:  third stage. At this point, all of the body’s resources are eventually depleted and the body is unable to maintain normal function. The initial symptoms may reappear (sweating, raised heart rate, etc.). Long-term damage may result, as the body’s immune system becomes exhausted, and bodily functions become impaired. The result can manifest itself in obvious illnesses such as ulcers, depression, diabetes, digestive system problems or cardiovascular problems.  It can also manifest as a chronic pain syndrome, guarding/avoidance behavior, and/or sleep disturbance.  Hopelessness can set in.

Chronic Stress and Cortisol

When the body’s HPA-axis cannot overcome a challenge and/or is chronically exposed to a threat, this system becomes overtaxed and can be harmful to the body and brain. An increased level of cortisol is one of the most dangerous outcomes of chronic stress.

Cortisol is an important hormone in the body, secreted by the adrenal glands and involved in some of the following functions: proper glucose metabolism, regulation of blood pressure, insulin release for blood sugar maintenance, immune function and inflammatory response. Normally, cortisol is present in the body at higher levels in the morning and is at its lowest level at night. Although stress is not the only reason that cortisol is secreted into the bloodstream, it has been termed “the stress hormone” because it’s also secreted in higher levels during the body’s ‘fight or flight’ response to stress, and is responsible for several stress-related changes in the body. Small increases of cortisol have some positive effects:  a quick burst of energy for survival reasons, heightened memory functions, a burst of increased immunity, lower sensitivity to pain, and helping to maintain homeostasis in the body.

 People are biologically ‘wired’ to react differently to stress.

While cortisol is an important part of the body’s response to stress, it is important that the body’s relaxation response be activated so the body’s functions can return to normal following a stressful event. Unfortunately, in our current high-stress culture, the body’s stress response is activated so often that the body doesn’t always have a chance to return to normal, resulting in a state of chronic stress, thus producing high chronic cortisol levels.

Higher and more prolonged levels of cortisol in the bloodstream like those in chronic stress have been shown to have negative effects, such as: 

• Impaired cognitive performance (loss or poor concentration, inability to complete tasks or heightened confusion in mildly stressful situations
• Suppressed thyroid function
• Blood sugar imbalances such as hyperglycemia
• Decreased bone density
• Decrease in muscle tissue
• Higher blood pressure
• Lowered immunity and inflammatory responses in the body, slowed wound healing, and other health consequences
• Increased abdominal fat, which is associated with a greater amount of health problems than fat deposited in other areas of the body.

When people feel stressed, stress hormones can be over-secreted, dramatically affecting the brain. Cortisol also plays a large part in post-traumatic stress disorder (PTSD) and memory. In a 2002 article in Biological Psychiatry regarding cortisol, PTSD and memory¹, cortisol was noted to work with epinephrine (adrenaline) to create memories of short-term emotional events.  This effect may serve as a means to help a person remember what situations to avoid in the future. However, long-term exposure to cortisol damages cells in the hippocampus and can create impaired learning ability. It has been shown that cortisol inhibits memory retrieval of already stored information.

Cortisol secretion varies among individuals. People are biologically ‘wired’ to react differently to stress. One person may secrete higher levels of cortisol than another in the same situation. Studies have shown that people who secrete higher levels of cortisol in response to stress also tend to eat more food, and food that is higher in carbohydrates, than people who secrete less cortisol.

¹“Depression. What happens in the brain?” Biological Psychiatry, 2002