Definition: Yoga can be defined as “control the faculties of the mind (chitta)”.

Sage Patanjali defines it as “Yogaschitta vritti nirodhah” or to control the faculties of mind/Chitta”.

Scriptures, including Vedas, Upanishads, Yoga Darshan, Manusmriti and others have described the following basis for the practice of Yoga to achieve the above goal as follows:

Besides the physical body, made up of elements of nature, we have nonphysical elements which leave the body with the soul when a person dies and stay with the soul. These elements are responsible for makeup of the personality and fate of a person along with the environment and genetic aspects upon rebirth.

These nonphysical elements are psychic and causal bodies.

The Psychic body is made up of 5 pranas, 5 senses of knowledge- gyanendria, 5 subtle elements- suksham bhut, Mind and Intellect. Manas, Buddhi, Chitta and Ahankar have also been collectively labelled as the Inner instrument or Antahakaran Chatushtaya. Practice of Yoga addresses all the bodies. This whole system has also been expressed as the 5 sheaths or layers which the Yogi goes deeper in, to finally make the soul pure with no external input and be in the state of Ananda or eternal peace and happiness.

Yoga Darshan, the main text for the practice of Yoga has 4 chapters or Padas, containing total of 195 sukta. There chapters are, Samaadhi Pad, Saadhan pad, Vibhuti Pad & Kevalya Pad.

The Yoga can be practiced in several different ways, but the main one called the Raj Yoga or Ashtaanga Yoga, as per Sage Patanjali consists of 8 steps/parts/stages. The whole emphasis is on first

making a fundamental correction in the life style of a person by creating a mental environment by teaching proper social and personal code of conduct. This is by following the Yama and Niyama. These 10 rules are similar to the10 principles laid out by Sage Manu while defining Dharma in the first book of Law or the conduct given to the humanity at large at the inception of creation of society. Following these guidelines, a person can have a better life style and habits including proper and timely meals, sleep pattern etc. This would lead to freeing the mind from s physical and mental stress. In addition, attainment of better human qualities would make one a better person, both in personal and social life. Through aasanaas, body would become pain free and physically more fit. Practice of pranayama or conscious breathing, would lead to a state of mental relaxation and better oxygenation of all body tissues and help prevent and improve or cure many illnesses. Deeper meditation through the stages of pratyaahar, dhaarna, dhyaan and samaadhi would further free the mind from external stress/influences leading to internalization and then focusing of mind on the inner self or atma/parmatma. So yoga is basically a holistic approach to living as a whole. Even in modern medicine, more and more emphasis is being given on prevention of disease and treating the person as a whole. Practice of Yoga is to be tailored based on an individual person’s needs.

Origin of disease/illness

In USA, about 4% or more people practice yoga. In order to understand the benefits of Yoga, it is important to understand why illnesses occur. We have 10 trillion cells in the body and 100 trillion bacteria living in our gastrointestinal system, mainly in colon. So, it is easy to understand that a holistic approach such as practice of yoga can be very effective. Research on various organ systems has proven that various levels of pains in body, hypertension, heart disease, various digestive, nervous system and mental disorders have their origin in coping with various levels of stresses in life. Positive thinking achieved through Yoga is self-empowering, resulting in better sense of wellbeing, both physically and mentally.

Although, the whole system of Ashtaanga Yoga is designed to be a systematic approach through its 8 parts, for simplification, I will first describe the mechanism of benefits of pranayama and then meditation. In conclusion, I will list the potential benefits as well.

Normally during breathing we utilize only a small portion of our breathing capacity called tidal volume. During deep inhalation we utilize what is known as inspiratory reserve volume and during deep exhalation we utilize expiratory reserve volume, in addition to the tidal volume. Therefore, starting from deep exhalation, tidal volume and deep inspiration, the total sum of these three parts is called vital capacity. In addition, there is still some air left in the lungs after deep exhalation, and this is known as residual volume. One can call upon even this part of the total lung capacity through the practice of yoga. It can easily be seen, therefore, how a 500 cc tidal volume can be maximized ten to eleven times up to 5.5 liters by advanced training.

Here are some of the articles I found on this subject through literature search.

Holding of breath at various levels: Baseline heart rate and both systolic and diastolic BP decreased after 4 weeks of practice of pranayama. This is probably through autonomic response to breath holding probably through increased vagal tone and decreased sympathetic discharges. (Indian Journal of Physiology and Pharmacology 1998)

Bhasrika Pranayama with rate of 6/minute, with 4 second inhalation and 6 second exhalation done for 5 minutes decreased both systolic and diastolic BP.

Yoga-better Oxygenation: There is some suggestion that yoga can increase blood flow and increase Hemoglobin Levels. Oxygen is carried in blood primarily as Oxy-Hemoglobin. Some oxygen is also dissolved in the plasma. This dissolved amount can be increased by pranayama.

Respiratory function tests have shown better parameters following yoga sessions. Strength of both inspiratory and expiratory muscles is increased.

Better overall tissue oxygenation benefits all major bodily functions. This leads to overall better work capacity, performance, a positive attitude in life and an overall better sense of wellbeing. This is true for those who are otherwise healthy as well as those with illnesses such as heart disease, hypertension, diabetes, arthritis etc.

Nervous System- Humans have about 100 billion neurons and 30-100 different chemicals or neurotransmitters in brain and about 10 of these chemicals do 99% of the work. Each neuron communicates with the next one through what is called a synapse, a gap where chemicals are liberated from the axon of one neuron to communicate with the dendrite of the next neuron by liberation of a chemical/neurotransmitter. Lot of what happens at a given moment depends on the net result of how many neurons are involved, what chemical is liberated, which parts of brain are involved in action and so forth. Some memories of experiences are left in parts of brain called the Amygdala and Hippocampus and other higher centres, which govern the reaction or the response of the person to the subsequent events in life. Though Yoga, modifications can be made in this response to tone down the hypothalamic-pituitary- adrenal system or adrenergic response with shift from sympathetic to parasympathetic activity. Research has shown that this shift from fight and flight to relaxation and mental peace through the practice of Yoga can lead to decrease in Steroid levels in saliva, blood Glucose, plasma renin, 24 Hr. Urinary nor- epinephrine/Epinephrine levels and decreased Heart Rate, Systolic and Diastolic BP as well.

Brain areas of relevance for Yoga and meditation are:

  1. Frontal lobe

  1. Parietal lobe

  2. Limbic System

  3. Reticular System.

Frontal Lobe is also called Attention Association Area (AAA). It deals with will-power, focus of

attention/energy and concentration. Prefrontal area is the brain’s top executive. It organizes responses to complex problems, guides behavior with verbal skills and houses networking memory. It is also connected to the limbic system and helps to mediate attention, emotion, and memory.

Parietal Lobe is called the Orientation Association Area (OAA). Receives and processes sensory information from the body. Deals with orientation in space and speed of objects. Distinction between self and world. It is also the seat of seat of mind and ego

Cingulate Gyrus- Emotion formation and processing, learning, and memory,

Parahippocampal Gyrus- Memory encoding and retrieval,

Hippocampus- Long term memory of facts and events.

Amygdala- Emotional memory and reaction to fear. It is larger in males

Thalamus- Two way relay station

Hypothalamus-maintains body’s body functions, such as BP, Weight, temperature and appetite Mammillary Body- relay signals to thalamus contributing to alertness and memory formation Reticular System: Through our senses, information of various types is being fed constantly to our brain

through our nerves. This information travels back and forth to our brains through the brain stem in a series of long nerve pathways called the reticular system. This plays an important role in regulating our autonomic nervous system. Reticular system constitutes an arousal mechanism that keeps the brain alert and keeps us awake. Information from the reticular system goes to part of brain called thalamus and then

on the brain.

Here is the summary of some of articles I found on this subject in searching through the literature. GABA is a chemical positively associated with relaxation and reduction of brain activity. In experienced yoga practitioners, brain GABA levels were measured by doing magnetic resonance spectroscopy. Levels were found to be 27% higher after a session of yoga. This suggests that the practice of yoga should be

explored as a treatment for disorders with low GABA levels such as depression (50% lower GABA levels in occipital cortex) and anxiety disorders. Future studies should compare yoga to other forms of exercise to help determine whether yoga or exercise alone can alter GABA levels.

“Division of Psychiatry, Boston University School of Medicine, Boston, MA 02118, USA”.

Brain size in meditators: Meditators showed significantly larger volumes of the regions which regulate emotions. These are: hippocampus, prefrontal cortex, thalamus, inferior temporal gyrus, and Rt. Insula. There was also a slowdown of decrease in putamen size with age.


Yoga inhibits posterior or sympathetic area of the hypothalamus, resulting in optimization of body’s sympathetic response to stressful stimuli and restores stress regulation in body. Yoga inhibits the areas of brain responsible for fear, aggressiveness and rage and stimulates the rewarding pleasure centers in the median forebrain and other areas leading to state of bliss and pleasure. Consistent yoga improves depression and increases serotonin levels and decreases MAO levels. Yoga therapy increases positive coping skills and builds self-esteem without harmful side effects.

Depression, stress and anxiety disorders arise from a dysfunction in the modulation of brain circuits which regulate emotional responses to potentially threatening stimuli which involve bottom-up activity from the amygdala, indicating the presence of potentially threatening stimuli, and top-down control mechanisms originating in the prefrontal cortex, signalling the emotional salience of stimuli. Level of neuronal inhibition

is down regulated in pathological anxiety states. Targeting the neuro-steroid-GABAA receptor axis represents an attractive target for the modulation of anxiety.

There is an intricate network of bi-directional relationships between the immune system and the brain. Depression has been found to alter the immune system. Immune system can influence the brain and behavior. Consequences of these effects on the brain include depression, anxiety, fatigue, psychomotor slowing, anorexia, cognitive dysfunction and sleep impairment.

Brain Waves

There are 4 types of waves in brain.

Beta Waves: occur when the brain is working on a goal oriented task. These are minimal during meditation.

Alpha Waves: A person who takes a break from a conference and walks in the garden is often in an alpha state. These also occur and in the posterior parts of the brain during meditation.

Theta Waves: EEG recordings during deep meditation showed extremely powerful Theta waves in the left prefrontal cortex. Also occur during dreaming.

Delta waves: These are present during sleep and at times during dreams. This indicates that sleep is distinct from meditation.

Yoga-Potential Benefits

The practice of Yoga teaches a person confidence, gives the ability to cope with life situations better, provides strength and relaxation and reduces illnesses at various levels.

  1. General sense of wellbeing and better muscular and overall physical strength.

  2. Discipline and better success and increased self-esteem.

Sleep disorders: Less chances of sleep apnea, better quality of sleep, needing less hours and provide better oxygenation to body tissues. It can also reduce snoring.

Anxiety and Depression: clearly beneficial. Self-awareness is increased with better energy level. The chances of suicides, homicides and other crimes can be reduced through the understanding of truth about life.

Substance abuse/Dependence: Yoga can reduce to eliminate dependence on drugs such as alcohol, pain medications, sedatives, hard core drugs, mood elevators, smoking and even tea or coffee Neurovascular and other nervous system disorders: such as stroke, muscle weakness and Headache including migraine.

Arthritic conditions: better posture, more mobility and reduced wear and tear. Beneficial in chronic pain conditions reducing dependence on medications with fewer side effects.

Cardiovascular: Heart attacks occur very early in the morning due to circadian rhythm. Concept of waking up very early decreases if not eliminates this phenomenon. By reducing sympathetic input (fight or flight response) and increasing parasympathetic activity, both systolic and diastolic BP decrease and this is beneficial for all the vital organs of body.

Digestive Function: Gastro-esophageal Reflux, abdominal distress of various levels and altered bowel movement habits, food allergies and food intolerances are quite common. Some forms of pranayama such as Kapal-Bhati have been shown to be beneficial in GERD.

Allergic disorders such as asthma, allergic rhinitis, skin allergies and immune disorders

Genito-urinary disorders such as altered menstrual cycle and dysmenorrhea

Endocrine disorders such as thyroid dysfunction, diabetes and obesity and metabolic syndrome

Various malignancies, prevention and possibly retardation of progress?

Good Habits: Doing Pranayama, Waking up early, Going to sleep early, Eating light, right, and the last meal at least three hours before going to sleep, Sleeping on the left side, Drinking a lot of water Avoiding processed foods and artificial drinks, chocolates, caffeine, soda, etc.

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