The art and science of yoga are perhaps as old as civilization itself.
In ancient Himalayas [Nepal & India], yogis developed powerful methods for attaining heightened states of consciousness. Today this system is called yoga, meaning “union.”
Union of what? From the scientific point of view, yoga unifies mind and body, putting them into balance. The resulting inner transformation is associated with changes in the brain and broader nervous system.
In exploring the neuroscience of yoga, this article focuses on the three core areas of practice: Asanas (Postures), Pranayama (Breathing), and collectively Dharana, Dhyana & Samadhi (Meditation).
When people think of yoga, they typically picture asanas, a staple of the modern westernized form of yoga. But asanas—literally meaning “seat” in Sanskrit—were initially designed to allow one to rest easily in a meditation posture for long periods.
Dr. Chintamani Gautam , Founder of the Nepal Yoga Academy, clearly states the purpose of asanas: they are designed to make the body fit for meditation. In other words, to achieve the full potential of yogic practices (samadhi, discussed later), one must have a healthy and pliable mind-body system.
Asanas enable this by calming the nervous system, training self-regulation, and boosting overall mental health.
It is no revelation that movement influences mental states. One need only jump up and down for a few seconds to feel the cognitive effects of physical activity.
Much of one’s mental suffering and instability comes from an ancient set of software in the brain and body commonly called the fight-or-flight response. To summarize, the amygdala (center of emotions in the brain) signals the hypothalamus, triggering a cascade of hormones like norepinephrine and cortisol and preparing the body for survival action.
While this stress response would have once kept us alive in the jungle, a modern tiger comes in the form of overdue bills. Anxious thoughts trigger the same fight-or-flight system without a prompt resolution. The resulting “allostatic overload” occurs when stress hormones like cortisol hang around too long, causing damage such as a weak immune system, high blood pressure, and cognitive decline.
Asanas and other areas of yoga train the ability to regulate this stress response, as shown by improvements in heart rate variability (HRV), a key indicator of physiological balance. This resulting state of homeostasis may result from the smooth, controlled body movements that would have been an evolved body-mind indicator for relaxation.
Additionally, research has found that the body reflects and stores mental states, including long-term trauma. Yoga works to relieve tension throughout the nervous system, and evidence suggests that it can help with trauma.
In Patanjali’s Yoga Sutras, he states very clearly how to perform asanas: stirum sukham asanam, meaning essentially “stability and enjoyment, those are the qualities of proper postures in yoga.” By steadying the body with mindful movements, one engages several key brain areas, including: 
As a moving meditation, asanas train one to observe the mind-body system in action, which leads to enhanced self-regulation. The brain learns to become aware of the body, called viscerosomatic processing. Overall, yoga trains meta-awareness, the ability to observe mental mechanics, commonly associated with the insula and ACC, among other brain regions.
In this way, one’s top-down cognitive processes (perceptions and ideas) integrate with bottom-up processes that can be automatic and maladaptive. The result is an enhanced ability to respond to harmful impulses and homeostatic disruptions, like stress. These abilities are likely trained throughout various yoga practices, not just asanas.
Asanas have been shown to help with a range of mental disorders, including anxiety, depression, autoimmune conditions, and pain syndromes. It isn’t easy to discern which mechanisms led to these outcomes, given that body and mind are interconnected. This same study proposed that the mental health benefits could result from increased vagal tone, reduced cortisol levels, and lower heart rate and blood pressure.
Exercise releases favorable neurochemicals in response to bodily movement, and it’s likely that yoga has similar effects. These include brain-region-specific increases in dopamine, serotonin, and acetylcholine.
Having calmed the mind through the gross physical body, the next area, pranayama, works with subtler energetic layers.
Pranayama roughly means “controlling the breath” or “freeing the energy,” depending on how you translate it. Prana is more than just the breath, better understood as vital force, like the Chinese concept of qi. From a scientific standpoint, this could be understood as the chemical and electrical energy that animates the nervous system. Prana can be directly experienced by practicing pranayama and other yogic methods.
Breathing provides the core ingredients of energy (via oxygen) used by cells to produce adenosine triphosphate (ATP). As Al Lee & Don Campbell put it in Perfect Breathing, “Every neuron, every synapse, every muscle feeds on the flame of your breath.” You can live without food for two months, water for a few days, but breathing for mere minutes. It’s that important.
By manipulating the breath, pranayama impacts your nervous system.
There are different types of pranayama. Each varies in terms of inhale, exhale, and retention length, as well as other factors, like pace and nostril side.
There are several stimulating yogic breathing exercises. Breath of Fire, a.k.a., kapalbhati, has been shown to decrease latency (for quick brain processing), increase amplitude (involvement of more neurons), and increase attention task scores by 32.5%, as well as reducing the degree of optical illusions. Humming Bee Breath, a.k.a., brahmari, elicits rare high-frequency gamma brainwave activity, a sign of heightened awareness. And Bellows Breath, a.k.a., bhastrika, was shown to significantly decrease impulsive responses on an attention task by 100%. However, it should be noted that these were small studies measuring short-term effects. Much further research is needed.
Slow yogic breathing, on the other hand, increases homeostatic properties, improves oxygen saturation, and lowers blood pressure. It is also associated with theta brainwaves (signs of relaxation) and increased alertness. Another calming technique, alternate nostril breathing, has been shown to increase spatial memory and grip strength.[14,15]
From a scientific perspective, it is difficult to parse out specific mechanisms, such as particular neurochemicals or networks in the brain. We might hypothesize, however, that kapalbhati’s hyperventilation increases alertness by activating the sympathetic nervous system. More calming pranayama, such as Alternate Nostril Breathing (nadi shodhana) and Breath Retention (kumbhaka) may increase vagal tone and decrease sympathetic activity.
One theory on the cellular mechanism of slower pranayama techniques suggests that it resets the autonomic nervous system through inhibitory signals and hyperpolarization currents in the heart, lungs, limbic system, and cortex. In other words, slow, deep breathing voluntarily puts the nervous system into a state of deep rest. As of yet, science has not found a physical basis for prana (subjectively felt inner energies). Doing so would likely help elucidate the underlying mechanics of yogic breathing methods.
The Hatha Yoga Pradipika states, “When the breath wanders, the mind also is unsteady. But when the breath is calmed, the mind too will be still…” Since a smooth, regulated breath can calm the nervous system, this checks out.
From a neuroscientific perspective, two core mechanisms of pranayama have been identified:
While voluntary control of the breath uses cortical top-down regulation, bottom-up regulation also occurs via the brainstem and vital centers. So the autonomic nervous system can both impact the brain and be consciously manipulated by the command centers of the brain.
Not surprisingly, such alterations in physiology bring about changes to mental states. Dr. Chintamani explains that pranayama helps control the mind, allowing for deeper states of meditation. This relates to one of the earliest definitions of yoga given by Patanjali: yoga means stopping the fluctuations of the mind (yogas chitta vritti nirodah). As you learn to control the rhythm and pace, the agitated fluctuations (vrittis) of the mind (chitta) come under control.
With the mind-body system stabilized and under conscious control from asanas and pranayama, it’s easier to enter deep states of meditation. The more gross outer body and inner energies having been calmed, we move to the subtlest levels of mind.
Three of the eight limbs of yoga relate to different stages of meditation, namely:
In this context, meditation means training one’s mind like a muscle. In fact, this may be a good analogy, as a study found that yogic meditation was associated with higher grey matter volume in the brain.
The mind begins unwieldy, distracted among a medley of thoughts and emotions. It’s entirely out of one’s conscious control as a default human condition. So meditation entails focusing the mind. In this case, the yogi brings their attention onto a single point of concentration, such as a physical object (e.g., a candle), sensation (e.g., sound vibrations), visualization (e.g., an archetype), mantra (e.g., Aum), or even the mind itself (i.e., pure awareness).
Dharana is the first stage of meditation, where one applies effort to keep their attention steady on an object. The mind constantly wanders off into thoughts, and the yogi is only successful for brief periods. Studies on dharana show that it appears to increase selective attention and visual scanning skills, suggesting that attention is indeed trainable.
Dhyana is stage two. At this point, the yogi can pay attention to their object without interruption for extended periods; attention stays on the object of meditation. Dr. Chintamani uses the analogy of dhyana as a steady stream of oil (stable attention) into a puddle versus the dribbling water (unstable attention) of dharana.
Here the neuroscience agrees with subjective reports of dhyana: it appears to be an effortless, relaxed state with reduced sympathetic nervous system activity. Compared to dharana, less effort is required to keep the mind focused. Dhyana also pertains to enhanced perception.
Finally, samadhi is the culmination of yogic meditative achievement, a joyful unification of mind. It has been described that subject and object merge into a singular flow of experience. Samadhi in the yogic traditions is an advanced state (actually further divided into three stages of absorption). There have been few scientific studies on its neural correlates. Scientists might be hard-pressed to find yogis both willing and capable of entering this state of consciousness while rigged to an EEG or crammed into a noisy fMRI machine.
One study on an experienced Buddhist monk found that samadhi appeared to activate his dopamine reward system, which matches the subjective feelings of bliss from such high levels of concentration. We might hypothesize that yogic samadhi would produce similar dopaminergic results. However, the point of samadhi is not to gain temporary bliss but rather self-transcendent liberation (kaivalya or moksha).
Yoga has always been a personal, inner exploration. Nonetheless, objective scientific measurements can add validity and elucidate mechanisms of the practice.
It is often difficult to parse out the components of yoga, as I’ve tried to do here because the practice was designed as a holistic system. We’re left with questions like: Was it the movement, breathing, or meditation that did the trick? Or perhaps all three worked synergistically?
For example, a combination of asanas, pranayama, and dharana were shown to increase brain derived neurotrophic factor (BDNF), a key player in brain cell growth and neuroplasticity.  And early evidence suggests that Sudarshan Kriya Yoga, which combines asanas, pranayama, and meditation, could effectively treat stress, anxiety, PTSD, depression, and other mental disorders.
There remains inconsistency in study design and the styles of yoga that are studied. Still, the emerging scientific picture shows both structural and functional neuroplastic change in areas linked to interoception, motivation, and self-control. Thirty-four peer-reviewed neuroimaging studies on yoga suggest an increase in grey matter in the insula (associated with self-awareness) and hippocampus (memory), activation of the prefrontal cortex, and functional changes to the default mode network (associated with rumination).
It should be noted that yoga, more broadly defined, includes other areas not addressed here, such as yogic diet (ahar) and various cleansing actions (shatkarma). This article covers only five of the eight limbs of Ashtanga Yoga, to say nothing of Bhakti Yoga, Gyana Yoga, and Karma Yoga, among many other types.
Moreover, while the health benefits of yoga are motivating, one ought not lose sight of its higher aims. The real science of yoga must be undertaken by the yogi. It is, after all, a map of inner experience that goes beyond objective measurements.
About the Author: Liam McClintock is the Founder of FitMind, a mental fitness company. He completed an RYT 500 Yoga Teacher Training through Nepal Yoga Academy and studied neuroscience at King’s College London.
 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.
 Van der Kolk, B. A. (2015). The body keeps the score: Brain, mind, and body in the healing of trauma. Penguin Books.
 Macy, R. J., Jones, E., Graham, L. M., & Roach, L. (2018). Yoga for trauma and related mental health problems: A meta-review with clinical and service recommendations. Trauma, Violence, & Abuse, 19(1), 35-57.
 Gard, T., Noggle, J. J., Park, C. L., Vago, D. R., & Wilson, A. (2014). Potential self-regulatory mechanisms of yoga for psychological health. Frontiers in human neuroscience, 8, 770.
Craig, A. D., & Craig, A. D. (2009). How do you feel–now? The anterior insula and human awareness. Nature reviews neuroscience, 10(1).
 Field, T. (2011). Yoga clinical research review. Complementary therapies in clinical practice, 17(1), 1-8.
 Basso, J. C., & Suzuki, W. A. (2017). The effects of acute exercise on mood, cognition, neurophysiology, and neurochemical pathways: a review. Brain Plasticity, 2(2), 127-152.
 Mason, H., Vandoni, M., Debarbieri, G., Codrons, E., Ugargol, V., & Bernardi, L. (2013). Cardiovascular and respiratory effect of yogic slow breathing in the yoga beginner: what is the best approach?. Evidence-Based Complementary and Alternative Medicine, 2013.
 Telles, S., Raghuraj, P., Arankalle, D., & Naveen, K. V. (2008). Immediate effect of high-frequency yoga breathing on attention.
 Telles, S., Maharana, K., Balrana, B., & Balkrishna, A. (2011). Effects of high-frequency yoga breathing called kapalabhati compared with breath awareness on the degree of optical illusion perceived. Perceptual and Motor Skills, 112(3), 981-990.
 Vialatte, F. B., Bakardjian, H., Prasad, R., & Cichocki, A. (2009). EEG paroxysmal gamma waves during Bhramari Pranayama: a yoga breathing technique. Consciousness and cognition, 18(4), 977-988.
 Telles, S., Yadav, A., Gupta, R. K., & Balkrishna, A. (2013). Reaction Time following Yoga Bellows-Type Breathing and Breath Awareness. Perceptual and Motor Skills, 117(1), 89–98. https://doi.org/10.2466/22.25.PMS.117x10z4
 Jerath, R., Edry, J. W., Barnes, V. A., & Jerath, V. (2006). Physiology of long pranayamic breathing: neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical hypotheses , 67 (3), 566-571.
 Naveen, K. V., Nagendra, R. N. H., & Telles, S. (1997). Yoga breathing through a particular nostril increases spatial memory scores without lateralized effects. Psychological reports , 81 (2), 555-561.
 Raghuraj, P., Nagarathna, R., Nagendra, H. R., & Telles, S. (1997). Pranayama increases grip strength without lateralized effects.
 Bhargava, R., Gogate, M. G., & Mascarenhas, J. F. (1988). Autonomic responses to breath holding and its variations following pranayama. Indian J Physiol Pharmacol, 32(4), 257-64.
Jerath, R., Edry, J. W., Barnes, V. A., & Jerath, V. (2006). Physiology of long pranayamic breathing: neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical hypotheses , 67 (3), 566-571.
 Herrero, J. L., Khuvis, S., Yeagle, E., Cerf, M., & Mehta, A. D. (2018). Breathing above the brain stem: volitional control and attentional modulation in humans. Journal of neurophysiology.
 Babu, M. G., Kadavigere, R., Koteshwara, P., Sathian, B., & Rai, K. S. (2020). Rajyoga meditation induces grey matter volume changes in regions that process reward and happiness. Scientific reports, 10 (1), 1-11.
 Telles, S., Singh, N., Gupta, R. K., & Balkrishna, A. (2016). A selective review of dharana and dhyana in healthy participants. Journal of Ayurveda and integrative medicine, 7(4), 255-260.
 Yamashiro, J. (2015). Brain basis of samadhi: the neuroscience of meditative absorption. The New School Psychology Bulletin, 13(1), 1-10.
 Hagerty, M. R., Isaacs, J., Brasington, L., Shupe, L., Fetz, E. E., & Cramer, S. C. (2013). Case study of ecstatic meditation: fMRI and EEG evidence of self-stimulating a reward system. Neural plasticity, 2013.
 Cahn, B. R., Goodman, M. S., Peterson, C. T., Maturi, R., & Mills, P. J. (2017). Yoga, meditation and mind-body health: increased BDNF, cortisol awakening response, and altered inflammatory marker expression after a 3-month yoga and meditation retreat. Frontiers in human neuroscience, 11, 315.
 Brown, R. P., & Gerbarg, P. L. (2005). Sudarshan Kriya Yogic breathing in the treatment of stress, anxiety, and depression: part II—clinical applications and guidelines. Journal of Alternative & Complementary Medicine, 11(4), 711-717.
 van Aalst, J., Ceccarini, J., Demyttenaere, K., Sunaert, S., & Van Laere, K. (2020). What has neuroimaging taught us on the neurobiology of yoga? a review. Frontiers in integrative neuroscience, 14, 34.
Journal by Liam McClintock [Neuroscientist]
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