Stress is defined as any disturbance or demand placed on the body to which the body must adjust or adapt, for example, temperature changes, toxic load, microorganism infection, physical trauma, emotional reactions etc.
The relationship between stress and fatigue often occurs along a continuum. In 1935, endocrinologist Hans Selye developed a theory of stress which he termed the ‘General Adaptation Syndrome’ (GAS). Based on his observations, Selye hypothesised that there were three phases of stress, each phase being largely controlled and regulated by the adrenal glands:
The alarm phase
The alarm phase involves the initial response to stress and is often referred to as the ‘fight-or-flight’ response. The fight-or-flight response is designed to counteract stress by mobilising the body’s resources for immediate action. Stress in the alarm phase is sudden, acute and short-lived. For example, it is the type of stress you experience just before you give a public speech or when you have a near-miss involvement in a car accident.
The fight-or-flight response is triggered by chemical messaging in the brain which stimulates the sympathetic nervous system (SNS) branch of our nervous system and signals the adrenal glands to upregulate cortisol and adrenaline secretions into the bloodstream. As a result, the following physiological reactions occur:
- heart rate and the force of heart contractions increase to improve blood flow to the brain and large muscles
- blood flow is shunted away from the skin and most internal organs, allowing increased blood supply to the brain and large muscles
- respiratory rate increases to allow increased oxygen to reach the heart, brain and large muscles
- sweat production increases to help lower body temperature
- production of digestive secretions is severely reduced because digestive activity is not considered critical for counteracting stress
- blood sugar levels rise dramatically to ensure there is enough energy supply to sustain the body.
As mentioned, stress in the alarm phase is generally sudden, acute and short-lived. After a brief period, cortisol and adrenaline secretions are downregulated or returned to normal and the resulting physiological reactions wear off.
However, in today’s modern society, we are increasingly and continually exposed to stress that elicits a fight-or-flight response, placing us in a perpetual state of fight-or-flight. Over time, the body adjusts or adapts to being in this state and this is what we call the resistance phase.
The resistance phase
In the resistance phase, the body has, to some degree, adjusted or adapted to repeated or ongoing exposure to acute stress. Chemical messaging signals the adrenal glands to continue the upregulation of cortisol and adrenaline secretions into the bloodstream to help sustain some form of ‘fight-or-flight’ reaction in the body to maintain productivity. In addition to the physiological reactions that occur with the fight-or-flight response, during the resistance phase the body also:
- begins to convert protein into energy to ensure the body has a large supply of energy to sustain it long-term
- retains sodium to help keep blood pressure elevated
- regulates chemical messaging signals to allow the body to continue to perform during an emotional crisis, accomplish strenuous tasks and fight infection as normal.
Although the continued upregulation of cortisol and adrenaline secretions is necessary to support the body during the resistance phase, sustained or prolonged elevated levels of these hormones over time begins to manifest as ill-health in the body. This can lead to poor health outcomes, including gut and digestive changes, heightened anxiety, poor sleep, menstrual cycle irregularities, nutritional deficiencies, fatigue, skin problems, weight gain and poor immune health. There is also a greater risk of developing significant diseases including diabetes, cardiovascular diseases and cancers. The more time an individual spends in the resistance phase, the greater the risk of progressing to the final phase of GAS – the exhaustion phase.
The exhaustion phase
Severely extended or prolonged time spent in the resistance phase of stress eventually leads to the exhaustion phase, which is often referred to as a state of ‘adrenal fatigue’. The exhaustion phase generally manifests as a partial or total collapse of bodily functions (i.e. immune function) or organs (i.e. adrenal glands). In the exhaustion phase, an individual typically has chronically elevated levels of cortisol and adrenaline in the bloodstream, however the adrenal glands are now no longer producing these hormones because they are completely depleted and physiologically unable.
After some time in this phase, there is a blunted response before cortisol and adrenaline levels begin to decline to a level below normal. This is as a result of the collapse of the adrenal glands, which are no longer producing these hormones. This is now often referred to as a state of ‘adrenal exhaustion’ and is characterised by extreme chronic, debilitating fatigue.
In our fast-paced society where stress is higher and more profound than ever before, it is important to understand the physiological effects stress can have on the body, especially when stress is persistent and prolonged.
As stress and fatigue occur along a continuum, it is critical to understand where you fall on this continuum in order to ensure you receive the correct and best possible treatment. This varies greatly depending on which phase, or sometimes which sub-phase, of GAS you are in.
Speak to one of our naturopaths. They can help you determine where you fall in GAS and advise you on what to do to support your adrenal health.
Written by Perri Baldwin BHSc