The vagus nerve is a main component of the parasympathetic nervous system, carrying signals from the digestive system to the brain, also known as the brain-gut axis (Breit, Kupferberg, Rogler & Hasler, 2018). The vagus nerve extends from the thorax (the neck) to the abdomen, relaying information from inner organs (e.g. lungs, gut, heart) to the brain. The parasympathetic nervous system is responsible for regulating states of rest, such as by dilating blood vessels, increasing bowel movement and glandular secretion. Vagal afferents signal from the brain to intestinal walls, causing adaptive responses for the body to maintain homeostasis, suggesting the important role of digestion with cognitive functions (Breit, Kupferberg, Rogler & Hasler, 2018).
Furthermore, the vagus nerve has anti-inflammatory effects through three separate pathways (Bonaz, Sinniger, & Pellissier, 2016); the hypothalamic-pituitary adrenal (HPA) axis, splenic sympathetic anti-inflammatory pathway, and the cholinergic anti-inflammatory pathway (CAIP). The HPA axis responds to stress responses, the splenic sympathetic anti-inflammatory release noradrenaline, and the CAIP has properties of fast neural conductance.
Vagus nerve stimulation (VNS) has been used to manage health and disease, proving beneficial for epileptic patients and with managing depression (Schlaepfer et. al, 2008). In regard to breathwork, studies have shown that yogic breathing and positive thought-oriented meditation can activate the vagus nerve (Streeter, Gerbarg, Saper, Ciraulo, & Brown, 2012; Kok et. al, 2013). Individuals experiencing physical symptoms of mental health problems can benefit from such breathwork, as the activation of the vagus nerve manages symptom severity (Rod, 2015). A longitudinal study into mindful slow breathing, by Earley, Chesney, Frye, Greene, Berman and Kimbrough (2014), found that such breathwork downregulated stress responses and controlled overactivity of the amygdala (Marek, Strobel, Bredy & Sah, 2013), and thus lowering physical symptoms of anxiety and PTSD amongst participants.
Additionally, Sudarshan Kriya Yoga (SKY) is a breathing technique which activates the vagus nerve, and thus changes the participant’s heart rate, improves cognition, and improves bowel movements (Zoe & Zope, 2013). Such improvements have been replicated in other studies, one study (Sharma, Barrett, Cucchiara, Gooneratne & Thase, 2017) involving patients managing depressive symptoms through SKY, without using antidepressants. Therefore, breathwork which stimulates vagal tones will have physical and mental benefits to those who regularly engage in them, due to the activation of the brain-gut axis.
Bonaz, B., Sinniger, V., & Pellissier, S. (2016). Anti-inflammatory properties of the vagus nerve: potential therapeutic implications of vagus nerve stimulation. The Journal of physiology, 594(20), 5781–5790.
Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders.Frontiers in psychiatry, 9, 44.
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Sharma, A., Barrett, M. S., Cucchiara, A. J., Gooneratne, N. S., & Thase, M. E. (2017). A Breathing-Based Meditation Intervention for Patients With Major Depressive Disorder Following Inadequate Response to Antidepressants: A Randomized Pilot Study. The Journal of clinical psychiatry, 78(1), e59–e63.
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