Stress, the immune system and yoga
Yoga can play a key role in breaking the connection between the stress stimulus and our response to it. By Dana Diament
The topic of immunity continues to be at the forefront of our minds, especially right now. But staying healthy and avoiding getting sick is a hallmark of our vitality and wellbeing, no matter what year it is.
It is highly likely you already have many habits and routines in place to bolster your immune system — things like eating well, supplementation through vitamins and herbs, practices such as yoga or dry brushing to boost your lymphatic system, eliminating or reducing your exposure to germs, and clearing out stress.
That last one may not be at the top of your list to help you avoid getting sick, but in this article, we’ll look at why it should be. If you or someone you know gets sick often despite all of their other healthy habits, their stress levels and more importantly their response to stress just might be the missing link.
You may have already heard that stress is not always a bad thing. When you face a real threat or danger – such as running away from a predator (e.g. a tiger), your body and mind will produce a stress response to help you meet the demand in your environment.
In the case of running away from a tiger, your body and mind adapt in order to get to safety as fast as possible. This is our fight or flight mode, and includes increased heart rate and breathing, more blood directed to muscles in your limbs, a boost to mental alertness and cognitive function, and other changes.
Stress levels are beneficial when they act to set off an alarm and signal the body to shift into an optimal performance zone.
When the demand is no longer present, in a healthy scenario the body returns to homeostasis and carries on with restorative and repair tasks such as digestion, sleep, relaxation.
Our nervous system’s ability to switch gears between the sympathetic nervous system (fight or flight) and the parasympathetic system (rest and repair) is referred to as parasympathetic tone, and ideally, we can ebb and flow between the two when needed and easily.
However, when the threat never goes away or a challenge is constantly appearing, the body remains in this heightened state of performance. This is when we start to become depleted and enter into an exhaustion stage marked by various physical, physiological, mental, and social symptoms. Two of these symptoms related to the immune system include low cortisol and low energy from adrenal fatigue, or excess cortisol and the suppression of immune system.
With long-term chronic stress, there is an immune dampening effect rather than adaptation and resilience, as described by Selye’s General Adaptation Syndrome.
Physiology of stress
The physiological connection between the immune system and the nervous system occurs via the hypothalamic-pituitary-adrenal axis or HPA axis. This includes a group of three glands from the nervous system and endocrine system that secrete hormones to help the body regulate the stress response. T
he hypothalamus is a small structure in the brain that sits above the brainstem and controls the release of hormones from the pituitary gland, which is just below the hypothalamus. The third gland is the pair of adrenals; sitting on top of each kidney is one adrenal gland.
When we experience stress, the hypothalamus releases corticotrophinreleasing hormone (CRH), which signals the pituitary gland to secrete adrenocorticotropic hormone (ACTH) into the bloodstream.
ACTH arrives at the adrenals, activating two areas of the adrenals. The inner layer, or adrenal medulla, secretes adrenaline and noradrenaline hormones, causing the desired and healthy physiological response described earlier to deal with the threat. The adrenal cortex, or outer layer of the adrenals, secretes glucocorticoids, commonly known as cortisol, to convert proteins and fats into glucose in order to replenish energy reserves during and after dealing with the threat.
Cortisol also suppresses the immune system; fighting infections and repairing the body becomes a low priority while there is a more pressing threat to deal with. Once there are high levels of cortisol in the blood, the HPA axis should shut off the stress response by reducing CRF and ACTH hormones, in turn reducing cortisol; this is known as the negative feedback mechanism.
When we perceive the stress to be constant or appearing regularly, the HPA axis can dysfunction. Rather than the negative feedback mechanism working to turn off the stress response, cortisol continues to be released, resulting in accumulated tissue levels of cortisol. This creates what’s called an allostatic load, a form of physiological wear and tear that includes a longer-term dampening of the immune system. In fact, a deficient or blunted HPA axis is observed in a wide range of autoimmune and inflammatory diseases.
Cortisol remains in the system until discharged through action such as talking, exercising, visualisation, meditation, yoga, painting, and more.
Studies have shown that yoga lowers cortisol and perceived stress. One study that compared African dance and Hatha yoga found both modalities reduced perceived stress and cortisol decreased in Hatha yoga. Another study found an increase of alpha waves and a decrease in cortisol during yoga in seven yoga instructors.
Alpha waves, which indicate you’re in a state of wakeful rest, were also seen to increase in practitioners of breathwork, signalling a reduced state of stress. Restorative yoga and introspective practices are also helpful modalities for the body to release chronic stress from the tissues.
The slow drip response of the adrenal cortex can be activated by our thoughts and emotions — this potentially makes our perception and memory of the threat more damaging than the stressor itself.
This is where a yoga practice can be extremely beneficial as you learn to broaden the gap between stimulus and response.
Whether you are meditating, doing physical postures or breathwork, you learn to bring your attention to one point, to slow down and cultivate patience.
You can use this mindfulness when you are off the mat to notice whether what you are perceiving as stress is real and needs immediate attention or is a remnant from the past and in actuality has already been dealt with, or something in the future that may not eventuate and doesn’t need your attention (and stress) at all.
Yoga elevates your awareness and helps you to become skilled in guiding and shaping your body’s automatic responses – such as the stress response – so that they serve you as nature intended, rather than negatively affecting your health and wellness.
In our modern world, where stressors feel like they are constant, perhaps one of the best ways to shift your thoughts and emotions around stress is to stop glorifying ‘busy’ and stop wearing stress like a badge of honour.
As you feel calm, clear and vibrant in your mind, the body is more likely to follow suit.
Dana Diament is a Yoga Medicine (yogamedicine.com) instructor who is passionate about blending eastern and western perspectives. Based in Byron Bay, Australia, she writes about yoga, meditation, health and anatomy and teaches workshops, group classes and therapeutic privates.