Yoga, Stress and Disease
The Science of How Yoga Works to Alleviate Stress Related Diseases
Stress is a Mind and Body Process
Stress is a part of life, working with it helps us to adapt and develop strength and resilience. Yet, exposure to stressors must be balanced with states of relaxation in order for us to be able to function optimally and build tolerance to whatever surprises life may bring.
When humans are subject to ongoing or extreme stress they can lose their ability to rest and recuperate. This is because our stress response systems can get stuck, it’s very much as if our foot is jammed on the accelerator and the brakes don’t work. If left unchecked, this situation can lead to problems.
Stress begins in the brain. Once a stressor (it could be mental, emotional or physical) is perceived an alarm signal is sent to the hypothalamus, a tiny brain structure that serves as the command and control centre of the brain. The hypothalamus manages our biochemical responses to stressors, with a view to overcoming the stressful incident (allostasis).
The Mighty Hypothalamus
The hypothalamus is tiny, however it plays a massively essential role in keeping the the autonomic nervous system (ANS), hormonal and immune systems in balance (homeostasis). It monitors functions essential to our life and wellbeing such as temperature, metabolism, sleep-wake cycles, electrolytes, blood sugar, hormones and exposure to stressors and compares them to basic set points (or norms). Managing all this is quite an incredible feat especially considering that the hypothalamus only weighs 4 grams (our total brain weight is around 1.4 kg)!
The ANS (Autonomic Nervous System)
The ANS is divided into two branches: the sympathetic nervous system (SNS) which activates processes for physical action (in every day life as well as for emergencies); and the parasympathetic nervous system (PNS) which initiates processes to aid rest, recovery, social engagement and digestion.
Rapid Response; Enduring Response
When stress is perceived the hypothalamus sends a signal through the SNS which initiates a rapid release of epinephrine and norepinephrine from the adrenal medulla into the bloodstream. This causes the activation of the “fight or flight” response and there is an immediate increase in heart rate, breath rate, blood pressure and blood flow to skeletal muscles. Systems that are non-essential for fighting or running away (immune, reproductive and digestive systems) are down regulated.
Following the initial adrenal stress response, is another slower more enduring stress response that is mediated by the Hypothalamus - Pituitary - Adrenal (HPA) axis. There is a chain of hormonal communication through these glands which culminates in the release of cortisol in the adrenal cortex.
How Stress Can Cause Disease
Cortisol then takes over the role of epinephrine to keep the SNS “stress response” going. The high cortisol can potentially cause prolonged elevated levels of blood sugar, which can be a precursor to diabetes. In addition, the elevated heart rate and blood pressure, due to the sympathetic (SNS) response, can increase the propensity to heart disease.
What is more, the SNS down regulates the reproductive, immune and digestive systems. So if the stress is not actively managed there can be an increase in disease or ailments in these systems. These might include problems such as disrupted menstrual cycles, a lowered ability to fight off viral infection or digestive issues such as irritable bowel syndrome (IBS) or chronic constipation.
How Yoga Can Help
This all sounds rather gloomy! However, yoga offers many practices that move the nervous system towards the relaxation response. Cortisol, epinephrine and norepinephrine are all needed to move the body strongly, whether to escape from danger, or to simply exercise. Thus strong, slow yoga posture work on the physical body (anamayakosha) can help the body to use up the excess blood sugar in the bloodstream that occurs during stress.
Using our breath (pranamayakosha) and mindful attention (manomayakosha) we can work with the ANS to activate the relaxation response. Each time we inhale we activate the SNS a little (the fight or flight response). Each time we exhale we activate the PNS a little (the relaxation response). By consciously lengthening the exhale we can nudge ourselves into relaxation response. Which means we’ll send the right signals to the hypothalamus to turn down the stress response.
Yoga Philosophy and Meditation
Yoga philosophy, in particular the observance of the yogic virtues: the yama and niyama, can help us to make wiser choices (vijnanamayakosha) for our health and wellbeing. For instance cultivating contentment (santosa) can help us to deal with stressful situations in a way that enables us to find a sense of agency in a world that often feels stressful, unjust and corrupt.
Meditation and deep relaxation also have a huge effect on the ANS. The doctor and researcher Dr Herbert Benson, conducted a series of experiments on meditators in the early ‘70s. These showed that twice daily meditation for 20 minutes, enabled subjects to reduce stress in general, and more specifically to reduce their blood pressure. He hypothesised that the meditation-induced relaxation response decreases and counteracts the SNS response associated with stress.
Please note, as Benson did, that yoga and meditation practices can be a valuable part of a treatment programme for chronic stress-related health conditions. However, it is important to consult a doctor if you are experiencing ongoing signs and symptoms of ill health and disease.
Dear Yoga Student,
Wow it’s been a hectic week! At points I did feel like the guy in the photo up above. I’m gearing up for the next module of my yoga therapy training. This article is part of my homework, I hope you enjoy it… isn’t the hypothalamus incredible? I think it is my new favourite brain structure.
So this week there is no Saturday class as I’ll be studying whilst the rest of the UK is celebrating! The Monday class is also not on as it’s half term.
The Tuesday chilled out Holistic Somatics on Zoom is there for you if you’d like to fully activate your parasympathetic relaxation response. Really there is no better way than yoga!
Enjoy your holidays and hope to see you soon!!
With love and good wishes,
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