Everyday demands of high-speed urban lives make it more and more difficult for many of us to constantly having to adapt to the demands of the environment. Many stressful events result in physiological changes and observation of this relation as the root of diseases is the focus of psychosomatic medicine that links mind with the body. Sometimes, the body knows best, and before our mind realizes that there has been a disbalance. Every one of us has an individual internal capacity to handle stress, that Daniel Siegel called “a window of tolerance”.
Physiologically, our reactions to stress are controlled by a major neuroendocrine system: hypothalamic–pituitary–adrenal (HPA) axis. It regulates many other body processes, including digestion, the immune system, mood and emotions, sexuality, and energy storage. The HPA axis integrates physical and psychosocial influences in order to allow our organism to adapt effectively to its environment, use resources, and optimize survival.
There are two modes to the stress response:
1/ The hypothalamus, via the pituitary, causes the adrenal cortex to release cortisol, which acts to release increased amounts of glucose from the liver’s glycogen stores. Cortisol release also causes retention of sodium and water by kidneys, increases blood volume and pressure, suppresses immunity, and reduces inflammation. Excessive levels are harmful as they can lead the body to use too much of its resources, damage tissues, and compromise immunity system.
2/ The adrenal sympathetic response is initiated by the hypothalamus. It causes the adrenal medulla to release epinephrine and norepinephrine. These two neurotransmitters increase blood flow to muscles and organs, allowing quick transportation of glucose to organs and muscles to allow the needed energy to fight or flee.
What controls this stress response?
We are equipped with an evolutionary physiological survival instinct called the fight or flight response coined by Walter Cannon. When faced with stressful situations our body releases hormones- epinephrine and norepinephrine to increase heart rate, breathing rate, blood pressure, metabolic rate, and blood flow to the muscles, gearing our bodies either to battle or to flee from the danger. Thankfully, our body is also inbred with the relaxation response (term by Herbert Benson) – an inducible physiologic state of quietude and ability to heal and rejuvenate itself. Both fight or flight response and relaxation responses are based on the mechanisms of the autonomic nervous system, respectively sympathetic and parasympathetic.
The autonomic nervous system maintains homeostasis by controlling heart rate, digestion, respiration, salivation, perspiration, sexual arousal, urination, and movement of blood flow to muscles and organs. Its two branches are sympathetic and parasympathetic nervous systems. They are antagonistic in nature and can be compared to gas and brake pedals in a car. The sympathetic nervous system uses lots of energy to prepare us to focus on stressful stimuli, therefore we call it a catabolic system. It breaks down things to get more resources and puts on hold processes that are calming or not vital to our survival (like nourishment, reproduction, or elimination of wastes). It is vital to our functioning, but its chronic activation can leave the body exhausted and depleted. To counterbalance, we have a parasympathetic nervous system that is dominant when we are resting, sleeping, and digesting, therefore it’s called an anabolic system that concentrates on rebuilding the body’s resources. In a healthy human being, it is the default system.
Yoga as a regulation practice can help us exit the fight or flight mode. Mindfulness can potentially make us more conscious and receptible to the bodily signs and cues of stress so that we can react to it before the results get too harming. In an ancient classical yogic text called Taittiriya Upanishad, there was a mention of a concept named koshas (“sheaths”). According to this concept, our true nature is covered and surrounded by five layers of awareness through which our experience of the world is filtered. They are the physical sheath (annamaya kosha), the sheath of vital life force and energy (pranamaya kosha), the mental or psychological sheath (manomaya kosha), the sheath of wisdom and intellect (vijnanamaya kosha) and the bliss body (anandamaya kosha). Imbalances within the five sheaths create psychological and physical suffering that take us away from our true wellbeing.
In the view of Vedantic philosophy, we all carry an individual fragment (atman) of universal consciousness (brahman). In the model of kosha, this atman resides in our innermost core, covered by five illusions (mayas). Our unique perception of reality comes through our identification with these layers of illusions. Our over-identification with aspects of the sheaths separates us from the knowledge of our true nature. Yoga therapy uses this model as a diagnostic tool to view a person holistically to understand the root of suffering (physical, mental, or psychological). It enables yoga therapists to embrace a multifactorial assessment of a person’s needs and move beyond a one-dimensional approach to treatment.