What is Stress? Stress is primarily a physical response, although most of our stress today comes from stressful mental states (imagined vs. real threats) that trigger a stress response. When stressed, the body thinks it is under attack and switches to 'fight or flight' mode, releasing a complex mix of hormones and chemicals such as adrenaline, cortisol and norepinephrine to prepare the body for physical action. Stress impacts our nervous system and activates the sympathetic response. Staying in an overactive state of sympathetic arousal wreaks havoc on our body’s systems. Stress hormones, namely cortisol, suppress the immune system and inflammatory pathways, rendering the body more susceptible to disease. A class of stress hormones called glucocorticoids represses the function of the T cells and B cells responsible for creating this defense.
Our autonomic nervous system (ANS) has two components: the sympathetic nervous system and the parasympathetic nervous system (which has two branches, ventral and dorsal). These three branches are in constant play to maintain our body’s homeostatic balance. When we’re relaxed, or engaged in restful activities like eating and digesting, it’s because our parasympathetic nervous system is active (the “rest-and-digest” response). On the other hand, it is the sympathetic nervous system that is responsible for stimulating activities associated with the “fight-or-flight” response. The ANS impacts cardiovascular, endocrine and even immune function, therefore, it is important to maintain its balance through stress reduction techniques.
The ANS is a bi-directional system, mediated by the vagus nerve (or Xth Cranial Nerve) that travels from our brain stem to our abdominal area. 80% of the nerve fibers of the vagus are sending information up to the brain, and 20% are sending messages from brain to body. This is a continuous process operating below our conscious awareness to maintain homeostasis. However, through awareness of breath and body sensations, we can exert our conscious will to regulate our stress levels, e.g. stressful vs. grateful thoughts, mindful orientation through the 5 senses, breathing practices, mindful movement and meditation.
Heart rate variability (HRV) is a relatively new method for assessing the effects of stress on your body. It is measured as the time gap between your heart beats that varies as you breathe in and out. Variability in heart rhythms is associated with physical and mental health. HRV measurements have been shown to be able to predict a likelihood of diseases occurring in the future (like diabetes or heart disease). A high HRV has been linked to good health and fitness, while low HRV is linked to stress, fatigue and even burnout. A low HRV is a sign of the sympathetic autonomic nervous system (also called the “fight-or-flight” system, or the stress system). And a higher HRV is associated with the parasympathetic nervous system (or the relaxed state). Optimal breathing ratio: Inhale for 6 seconds, exhale for 6 seconds or 5 breaths per minute.
A large component of immune response takes place in the fascia, which is a type of connective tissue that surrounds all muscles, bones and organs, and connects different parts of the body together, providing structure and coordinating movement. It’s a matrix of communication between cells, tissues and organs. The fascia is compromised under stress. Yoga and relaxation creates fluidity in the fascia, allowing it to provide immune protection from pathogens.