Yoga Therapy is a way of working one to one with the individual. In moving ahead in this field and making it more accessible to the community at large, it can be valuable to understand the biomedical and biopsychosocial aspects of mind-body medicine and the latest research in the field. To make the latest research more accessible to yoga and meditation teachers and therapists, at BIYOME, we break it down into 6 evidenced based research findings that makes Yoga, Yoga Therapy and Mindfulness Meditation a proven way of bringing the individual back to health by entering into a state of yoga and/or meditation.
Mindfulness Meditation, based on Buddhist practices, is the practice of bringing one’s focus to the breath, body and present moment. Recently, much research has gone into studying the innumerable positive benefits of this practice that delivers a more peaceful and tranquil body and mind. Through the research behind what we call the six conduits of a connected mind one can understand how truly complex and interconnected all bodily systems are, and how mindfulness meditation can help bring them all to a healthier balance.
These six conduits are as follows:
- The vagus nerve
- The heart-brain connection
- Heart rate variability (HRV)
- The hypothalamic-pituitary-adrenal (HPA) axis
- The gut-brain axis and
In this article, a brief overview and explanation of each conduit will be given. Their interconnectedness and relation to mindfulness meditation and yoga therapy will then be explored.
To begin, the importance of the vagus nerve should be discussed. The vagus nerve is the tenth cranial nerve, and interacts with the digestion, immune and cardiovascular systems (Ardell et al., 2015; Brack et al., 2004; Chang et al., 2015; Maier et al., 1998). The nerve plays a major role in relaying information that is occurring in the body to the brain, with 80% of its fibers acting as ascending sensory neurons (Chang et al., 2015). For example, the brain receives status updates of the immune system’s cytokines through vagus nerve stimulation (Maier et al., 1998). Meditation is also extremely intertwined with the processes of the vagus nerve as the major source of all nerve innervations in the lung derive from the vagus nerve (Chang et al., 2015). Vagal tone has also been shown to significantly increase compared to control of placebo through the practice of yoga (Khattab et al., 2007). This connection likely explains many of the relationships breathing, yoga and meditation has on the multitude of bodily systems also connected to the vagus nerve.
One such system is the all-important heart. The interaction between the heart and brain is extremely complex, involves many neurons and has the most communication pathways to the brain compared to any other organ in the body (Cameron, 2002). The vagus nerve plays an important role in autonomic nervous system (ANS) interaction with the heart. Stimulating the vagus nerve has been shown to affect heart rate in multiple studies (Ardell et al., 2015; Brack et al., 2004; Maier et al., 1998). Not only can the brain affect the heart, but the heart can have an affect on our brain and emotions. Studies have shown that heart rate can determine our emotional experience. An example of this is seen in panic disorders where physiologic aspects of the disease are created by cardiac arrhythmias (Mccraty et al., 2009). The heart and brain can both affect each other, and the harmony between both is of extreme importance. Heart health has been shown to be improved considerably through yoga by causing a reduction in heart rate, blood pressure and BMI (Sivasankaran et al., 2006). Meditation studies have shown that heart beats and brain waves synchronize during the practice (Montoya et al., 1993). Further suggesting mindfulness meditation’s ability to bring harmony to the body and mind.
Another important aspect of the heart brain relationship is heart rate variability (HRV). HRV is a measure of beat-to-beat variability performed by the heart. It is regulated by the ANS and primarily mediated through the vagus nerve through parasympathetic nervous system (PNS) activity (Krygier et al., 2013). The capability of variability is indicative of the body’s ability to adapt to environmental demands, regulate emotions, and be reduced in patients with cardiovascular disease (Krygier et al., 2013). In other words, an increase in PNS tone can have positive influences on HRV, thereby increasing heart and body health. Multiple studies have shown that through meditation, this increase in PNS activity and therefore HRV can be achieved (Nesvold et al., 2012; Phongsuphap et al., 2008; Wu & Lo, 2008). Additional benefits of meditation have been found, including the increase of baroreflex sensitivity through the same mechanisms which improve gas exchange within the lungs (Phongsuphap et al., 2008). A decreased HRV has also been found to be a symptom of depression and can be alleviated through yoga (Karavidas et al., 2007; Khattab et al., 2007; Streeter et al., 2018).
Clearly, the heart is greatly influenced by the vagus nerve and therefore function can be improved through mindfulness. However, this is not the only system affected. The HPA axis is also greatly affected. The HPA axis can be thought of as one of the main branches of the stress system of the body. The ANS comprises the sympathetic nervous system (“fight or flight response”) and the parasympathetic nervous system (“rest and digest response”). They are used in our body’s system for survival. The ANS system is the neuronal side of our stress system, and the HPA axis is the hormonal side of the system (Pascoe et al., 2020). In brief, when the body is in stress, the hypothalamus in the brain secretes corticotropin-releasing factor (CRF) which triggers the pituitary gland to produce and release adrenocorticotropic hormone (ACTH). ACTH stimulates the release of cortisol, which is the stress hormone that affects the rest of the body (Geiser, 1989). The overuse of this system can have many negative consequences on bodily health. ACTH decreases Natural Killer (NK) cells which fight cancer, cortisol decreases T cell activity and reduces lymphocyte response in the immune system (Geiser, 1989). In short, chronic stress is a strong indicator of poor health and increases the risk of illness (Ader & Cohen, 1993; Cohen, Sheldon,Williamson, 1991; Geiser, 1989). Multiple research studies have shown that yoga decreases the release of these stress hormones such as cortisol, catecholamines and renin-angiotensin (Riley & Park, 2015), indicating that it is a practice that can greatly reduce stress in life while increasing overall bodily health.
The relationship of mind and body in terms of immune function has developed into the field of psychoneuroimmunology. Psychoneuroimmunologists study the relationship between the emotional state of the mind and how it affects immune function, and vice versa. Meditation is able to counteract these effects by lowering cortisol and other stress related hormones, while increasing NK cells and leukocytes within the immune system (Moraes et al., 2018). Meditation is one of the most powerful and natural tools humans have to combat chronic stress and anxiety. Doing so will not only heal the mind and make it feel better, but at the same time will make the body healthier and less prone to illness.
The gut and brain also share a deep connection which affects the health of both. A healthy gut wall selectively allows nutrients into our body while excluding harmful molecules such as pathogens. Stress can have a drastic effect on gut microbiota health, thereby increasing the number of pathogens that make it inside of our body and can cause illness (Househam et al., 2017). Meditation, through its ability to alleviate stress, can aid in preventing this from occurring. A clinical example of this is the use of meditation and yoga to alleviate symptoms of irritable bowel syndrome (Kavuri et al., 2015; Schoultz et al., 2015).
The body and mind interact in a complex dance of physiologic balance. Too much stress for example can have a multitude of negative consequences harming the cardiovascular system, immune system and digestive system. Furthermore, when one system is unhealthy, consequences will befall onto the others as well. The six conduits of a connected mind remind us that through meditation and yoga, we can gain better insight and balance for our bodily systems, promoting greater health and wellbeing.
Meditation as Medicine ~ 6 Mind Body Conduits (live-streamed recording)
Ader, R., & Cohen, N. (1993). Psychoneuroimmunology: Conditioning and Stress. Annual Review of Psychology, 44(1), 53–85. https://doi.org/10.1146/annurev.ps.44.020193.000413
Ardell, J. L., Rajendran, P. S., Nier, H. A., KenKnight, B. H., & Armour, J. A. (2015). Central-peripheral neural network interactions evoked by vagus nerve stimulation: functional consequences on control of cardiac function. American Journal of Physiology-Heart and Circulatory Physiology, 309(10), H1740–H1752. https://doi.org/10.1152/ajpheart.00557.2015
Brack, K. E., Coote, J. H., & Ng, G. A. (2004). Interaction between direct sympathetic and vagus nerve stimulation on heart rate in the isolated rabbit heart. Experimental Physiology, 89(1), 128–139. https://doi.org/10.1113/expphysiol.2003.002654
Cameron, O. G. (2002). Visceral Sensory Neuroscience: Interoception. In Oxford University Press. Oxford University Press.
Chang, R. B., Strochlic, D. E., Williams, E. K., Umans, B. D., & Liberles, S. D. (2015). Vagal sensory neuron subtypes that differentially control breathing. Cell, 161(3), 622–633. https://doi.org/10.1016/j.cell.2015.03.022
Cohen, Sheldon,Williamson, G. M. (1991). Stress and infectious disease in humans. Psychological Bulletin, 109(1), 5–24. https://psycnet.apa.org/buy/1991-12984-001
Geiser, D. S. (1989). Psychosocial influences on human immunity. Clinical Psychology Review, 9(6), 689–715. https://doi.org/10.1016/0272-7358(89)90018-4
Househam, A. M., Christine, ;, Peterson, T., Mills, P. J., & Chopra, D. (2017). The Effects of Stress and Meditation on the Immune System, Human Microbiota, and Epigenetics.
Karavidas, M. K., Lehrer, P. M., Vaschillo, E., Vaschillo, B., Marin, H., Buyske, S., Malinovsky, I., Radvanski, D., & Hassett, A. (2007). Preliminary results of an open label study of heart rate variability biofeedback for the treatment of major depression. Applied Psychophysiology Biofeedback, 32(1), 19–30. https://doi.org/10.1007/s10484-006-9029-z
Kavuri, V., Raghuram, N., Malamud, A., & Selvan, S. R. (2015). Irritable bowel syndrome: Yoga as remedial therapy. In Evidence-based Complementary and Alternative Medicine (Vol. 2015). Hindawi Publishing Corporation. https://doi.org/10.1155/2015/398156
Khattab, K., Khattab, A. A., Ortak, J., Richardt, G., & Bonnemeier, H. (2007). Iyengar Yoga increases cardiac parasympathetic nervous modulation among healthy yoga practitioners. Evidence-Based Complementary and Alternative Medicine, 4(4), 511–517. https://doi.org/10.1093/ecam/nem087
Krygier, J. R., Heathers, J. A. J., Shahrestani, S., Abbott, M., Gross, J. J., & Kemp, A. H. (2013). Mindfulness meditation, well-being, and heart rate variability: A preliminary investigation into the impact of intensive vipassana meditation. International Journal of Psychophysiology, 89(3), 305–313. https://doi.org/10.1016/j.ijpsycho.2013.06.017
Maier, S. F., Goehler, L. E., Fleshner, M., & Watkins, L. R. (1998). The role of the vagus nerve in cytokine-to-brain communication. Annals of the New York Academy of Sciences, 840(1), 289–300. https://doi.org/10.1111/j.1749-6632.1998.tb09569.x
Mccraty, R., Atkinson, M., Tomasino, D., & Bradley, R. T. (2009). The Coherent Heart Heart-Brain Interactions, Psychophysiological Coherence, and the Emergence of System-Wide Order. In REVIEW December (Vol. 5, Issue 2).
Montoya, P., Schandry, R., & Miiller, A. (1993). Heartbeat evoked potentials (HEP) : topography and influence of cardiac awareness and focus of attention. In Electroencephalography and clinical Neurophysiology (Vol. 88).
Moraes, L. J., Miranda, M. B., Loures, L. F., Mainieri, A. G., & Mármora, C. H. C. (2018). A systematic review of psychoneuroimmunology-based interventions. Psychology, Health and Medicine, 23(6), 635–652. https://doi.org/10.1080/13548506.2017.1417607
Nesvold, A., Fagerland, M. W., Davanger, S., Ellingsen, Ø., Solberg, E. E., Holen, A., Sevre, K., & Atar, D. (2012). Increased heart rate variability during nondirective meditation. European Journal of Preventive Cardiology, 19(4), 773–780. https://doi.org/10.1177/1741826711414625
Pascoe, M. C., Thompson, D. R., & Ski, C. F. (2020). Meditation and Endocrine Health and Wellbeing. In Trends in Endocrinology and Metabolism (Vol. 31, Issue 7, pp. 469–477). Elsevier Inc. https://doi.org/10.1016/j.tem.2020.01.012
Phongsuphap, S., Pongsupap, Y., Chandanamattha, P., & Lursinsap, C. (2008). Changes in heart rate variability during concentration meditation. International Journal of Cardiology, 130(3), 481–484. https://doi.org/10.1016/j.ijcard.2007.06.103
Riley, K. E., & Park, C. L. (2015). How does yoga reduce stress? A systematic review of mechanisms of change and guide to future inquiry. Health Psychology Review, 9(3), 379–396. https://doi.org/10.1080/17437199.2014.981778
Schoultz, M., Atherton, I., & Watson, A. (2015). Mindfulness-based cognitive therapy for inflammatory bowel disease patients: Findings from an exploratory pilot randomised controlled trial. Trials, 16(1). https://doi.org/10.1186/s13063-015-0909-5
Sivasankaran, S., Pollard-Quintner, S., Sachdeva, R., Pugeda, J., Hoq, S. M., & Zarich, S. W. (2006). The effect of a six-week program of yoga and meditation on brachial artery reactivity: Do psychosocial interventions affect vascular tone? Clinical Cardiology, 29(9), 393–398. https://doi.org/10.1002/clc.4960290905
Streeter, C., Gerbarg, P. L., Nielsen, G. H., Brown, R. P., Jensen, J. E., Silveri, M., & Streeter, C. C. (2018). Effects of Yoga on Thalamic Gamma-Aminobutyric Acid, Mood and Depression: Analysis of Two Randomized Controlled Trials. Neuropsychiatry, 8(6), 1923–1939. https://doi.org/10.4172/Neuropsychiatry.1000535
Wu, S.-D., & Lo, P.-C. (2008). Inward-attention meditation increases parasympathetic activity: a study based on heart rate variability. Biomedical Research, 29(5), 245–250. https://doi.org/10.2220/biomedres.29.245