How Yoga Enhances The Glymphatic And Lymphatic System To Clear Potentially Neurotoxic Waste And Thereby Help Steady The Fluctuations Of The Mind.

Discussion and Studies

T.K.V Desikachar, modern master of yoga therapy, has stated that 90% of yoga therapy is waste removal. Leslie Kaminoff [1], student of T.K.V Desikachar, and coauthor Amy Matthews equates the Sanskrit terms prana and apana to the physiological processes of bringing nourishment into a living organism and the removal of waste. The authors further explain that prana is a verb interpreted to mean the following actions: to breath, to live and to nourish, as well as the process that brings nourishment in. This is balanced by apana, which has been translated to mean away, off or down. As such apana could also mean the action of elimination, as well as referring to the actual waste.  

Neuroscientist Jeff Iliff [3] from the University of Rochester Medical Center explains that cells need nutrients and oxygen to harness energy to perform, and they also create waste that must be cleared for cells to continue effectively functioning. The circulatory system through its vast network of blood vessels that branch into all tissues, delivers the nutrients and oxygen to cells of the body and brain, and the lymphatic system solves the problem of metabolic waste clearance through its parallel network of vessels that mops up proteins and wastes between the cells. After interstitial fluid, lymph, has been correctly filtered, the clean fluid flows back into the blood of the circulatory system. However, until recently it has been unclear as to how the brain solves waste clearance, as there was no evidence of a lymphatic system in the brain. With the brain demanding a whopping ¼ of the body’s entire energy for its intense electrical uses, despite only accounting for 2% of the body’s mass, the resulting waste is substantial and must be cleared.  

Maiken Nedergaard, senior author along with Iliff and colleagues [2] set out to uncover how the brain solves its waste problem, and through using in vivo two-photon imaging to trace the movements of fluorescent markers, they showed that during sleep cerebrospinal fluid pumps through the brain and flows along the outside of all the blood vessels in the brain in a system of hydraulic “pipes”, and that the fluid enters inter-cellular spaces in the brain tissue, collecting waste en route. They also discovered that proper function of these vessels depends on the movement of water around the brain, which are carried out by glial cells called astrocytes, and it is this essential role of glia cells that inspired the name Glymphatic System.

During sleep cells themselves shrink to further increase the inter-cellular spaces by up to 60%, thereby making more space between cells for the fluid to rush in and mop up waste. Hence Iliff [3] states that the repurposing of the blood vascularization in the brain to also be used as a path for cerebrospinal fluid, immune cells and waste clearance, is a clever design feature to best make use of space. It’s believed that the brain shifts into cleaning mode during sleep, as when awake the brain is too busy with daily tasks and functions. Numerous types of proteins can build up and aggregate between cells in the brain, and have been linked to neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease. Illiff and colleagues [2] specifically focused on measuring the clearance of amyloid- beta, an abnormal protein aggregation linked to Alzheimer’s disease, and proved that it does move through the glymphatic system far more rapidly with the influx of cerebrospinal fluid that flows through the brain during sleep.  

Worsening sleep quality and duration are associated with a greater amount amyloid-beta and other protein variants in the brain, and hence studies suggest that good quality sleep is needed to clear an aggregation of proteins and possibly prevent the development and worsening of neurological disorders.

How can yoga promote and improve sleep?

Yoga inspires one to focus on the breath, movement and on the present, which promotes relaxation. Studies have shown that including yoga in the daily routine of elderly people does help improve the quality of sleep, as well as quality of life [4,5]. Restorative postures along with savasana, pranayama, and meditation encourage pratyahara, a turning inward of the senses which has proven to promote the parasympathetic nervous system [6,7], relaxation response; with lowered cortisol levels, breathing and heart rate, as well as decreases blood pressure and the after-effect being improved sleep.

In a further study by Nedergaard and Helene Benveniste, a scientist at Yale University, [8] it has also been found that the position in which one sleeps contributes to more waste clearance of the glymphatic system. Waste is removed least efficiently sleeping in an upright position and lying prone on one’s stomach. Sleeping on one’s back is more favourable, and sleeping on one’s side allows for optimal waste removal. Reasons for the more favourable side-sleeping position is still not clear, however Nedergraad believes it must be connected to the mechanical functioning of the lymphatic vessels and valves. 

How can yoga help a person feel more comfortable and at ease to sleep on their sides?

One of the most apparent benefits of yoga is improved flexibility, with the continued practice improving the mobility of muscles and connective tissue. This in turn is thought to be one of the reasons that yoga reduces aches and pains, and will therefore also contribute towards one being comfortable to sleep on one’s side. During a yoga practice joints are moved through their full range of motion, which promotes increased synovial fluid and blood flow, bringing fresh nutrients and oxygen to these regions. Asana also helps increase muscle mass and strength, which protects and lessens pain associated with conditions such as arthritis and osteoporosis. Numerous studies have shown that asana, pranayama and meditation reduced pain in people with arthritis, back pain, musculoskeletal problems and other chronic conditions. [9-14].

Lymphatic vessels were only discovered in the central nervous system in 2015 [15,16] by a team led by Antoine Louveau and Jonathan Kipnis of the University of Virginia School of Medicine. Using high-powered microscopes they examined layers of tissue that cover the brain, meninges, of mice and noticed vessel-like patterns resembling that of the lymphatic system. Dye was then injected into mice, which the scientist tracked, and revealed that these vessels carried cerebrospinal fluid and immune cells along veins in the sinuses and deep cervical lymph nodes. The brain is now seen to have both a glymphatic system, and a secondary deep lymphatic system to further drain cerebrospinal fluid and assist in both waste clearance and immunity. “We think these vessels may play a role in pathogenesis of neurological conditions that have an immune component,” Kipnis says.

Can yoga help support the immune system?

Stress has been proven to compromise the immune system and makes a person more vulnerable to diseases. “Stress influences the immune response presumably through the activation of the hypothalamic-pituitary adrenal axis, hypothalamic pituitary-gonadal axis, and the sympathetic-adrenal-medullary system. Various neurotransmitters, neuropeptides, hormones, and cytokines mediate these complex bidirectional interactions between the central nervous system (CNS) and the immune system. The effects of stress on the immune responses result in alterations in the number of immune cells and cytokine dysregulation” [17]. Yoga promotes tranquility of the mind, relaxation and a sense of wellbeing shifting the balance to the parasympathetic nervous system. Furthermore yoga and meditation could help regulate the cytokine levels and therefore the immune responses during stress [17].

The mechanisms assisting the flow of cerebrospinal fluid are still not fully known. Cerebrospinal fluid circulates from the choroid plexus through brain ventricles to the brain’s outer surface in the subarachnoid spaces and then drains into venous bloodstream and cervical lymphatics. The groundbreaking studies revealing the glymphatic system show that cerebrospinal fluid also enters the brain tissue along para-arterial route and exits through paravenous spaces into the subarachnoid. 

A recent study [18] investigated how cerebrospinal fluid flow is regulated in humans, and applied a real-time magnetic imaging technique at high spatial and temporal resolution in healthy human subjects. During inspiration they observed significant flow of cerebrospinal fluid, whereas holding the breath suppressed it. The current results of this study identify inspiration as the most essential driving force for cerebrospinal fluid in humans.

Can yoga improve inspiration and therefore the flow of cerebrospinal fluid?

Yoga helps bring a person’s attention to breathing and promotes slow deep breathing, which has been proven to increase the cardiac-vagal baroreflex sensitivity (BRS), improving oxygen saturation and lowering blood pressure [6,19]. Studies have also show that yoga, meditation and pranayama can improve vital capacity, maximal inspiratory pressure, and maximal expiratory pressure and thereby improve lung function even with patients suffering with chronic obstructive pulmonary disease[19].

Conclusion

Yogas chitta vritti nirodha, Patanjali’s yoga sutra 1.2, refers to stilling the mind to experience union and the absolute truth of reality.

The mind’s fluctuations, vritti, must be stilled or quieted, nirodha, and the murkiness of being removed in order to clearly be in one’s ultimate truth of pure consciousness, chitta. Whereby the self has pure cognizance that the divine is within everything and that all is one. Recent studies have linked the aggregation of proteins in the brain to neurodegenerative diseases and propose that good quality sleep is needed for the glymphatic system to wash cerebrospinal fluid through the brain and clear out, with the help of the Lymphatic System, these potentially neurotoxic waste products. In this paper I propose that the physical clearing, setting aside of waste, apana, is essential to enable life force, prana, to flow and for the brain to optimally function. A healthy functioning brain will help one understand, still and eventually master the fluctuations of the mind-field, to enable self-realization and union with pure consciousness.

References:

[1]Kaminoff, L & Matthews, A ; 1958, Yoga Anatomy, USA: Human Kinetics.

[2]Iliff JJ1, Wang M, Liao Y, Plogg BA, Peng W, Gundersen GA, Benveniste H, Vates GE, Deane R, Goldman SA, Nagelhus EA, Nedergaard M.15 A Paravascular Pathway Facilitates CSF Flow Through the Brain Parenchyma and the Clearance of Interstitial Solutes, Including Amyloid β. August 2012. Sci Transl Med.

 Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22896675.

[3]Jeff Iliff. 2014.One More Reason To Get A Good Night Sleep. Retrieved from https://www.ted.com/talks/jeff_iliff_one_more_reason_to_get_a_good_night_s_sleep

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[15] Antoine Louveau, Igor Smirnov, Timothy J. Keyes, Jacob D. Eccles, Sherin J. Rouhani, J. David Peske, Noel C. Derecki, David Castle, James W. Mandell, Kevin S. Lee, Tajie H. Harris and Jonathan Kipnis. Structural and functional features of central nervous system lymphatic vessels, Nature, July 2015, vol. 523. Retrieved From
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