Yoga Research Foundation

Psychophysiological Effects of Nadi Shodhana Pranayama

Dr Swami Nirmalananda Saraswati

Nadi shodhana pranayama, with its various stages and combinations, is a unique practice that covers the full spectrum of applications, starting from the basic application of purification to preparing pranamaya kosha, the pranic body, for higher spiritual progress. We present here some thoughts on its basic application, suggested by its name, purification of the nadis.

Purification and nadi shodhana pranayama

It is essential to prepare the body-prana-mind complex to an optimum level before embarking upon higher yogic sadhanas or trying to realize one's potential. The preparation includes purifying the body of various dietary and metabolic waste products and the mind of impurities such as mala, the six enemies of passion, anger, pride, delusion, jealousy and greed. Then one has to control vikshepa, the oscillating nature of the mind, and remove avarana, wrong understanding. Wrong understanding is due to the kleshas,the five afflictions: ignorance, I-ness, attachment, repulsion and fear of loss.

There are many important purification practices in yoga, including the shatkarmas and the yamas and niyamas,as well as pranayamas. These practices work variously on the physical, mental and pranic dimensions of the human being, but the effects are experienced at all levels. Nadi shodhana pranayama, alternate nostril breathing, is the most commonly practiced pranayama. It is an importantpurification practice because it clears obstructions in the flow of prana in the nadis.

According to the Hatha Yoga Pradipika (2:5) and Gheranda Samhita (5:32), the yogi is ready to practice kumbhaka, breath retention, only after the nadis and chakras are purified. In raja yoga and hatha yoga, pranayama practices always precede meditation practices. This implies that every hatha and raja yoga aspirant has to practice and perfect nadi shodhana pranayama on the yogic journey.

Cause of obstruction in the nadis

When a person knowingly or unknowingly misuses the body-mind apparatus for a considerable period of time, the three doshas or humours, kapha, vata and pitta, become imbalanced, blocking the free flow of prana in the nadis. These impurities are the waste and residue of sensual living and over-indulgence in desires. Blockages in the nadis result from:

  1. Lack of adequate physical movement
  2. Incorrect posture
  3. Pooling of prana in one area depriving the other areas, e.g. in occupations demanding intense and prolonged mental activity or only a set pattern of movement or posture
  4. Harmful diet and products of digestion, e.g. acidic diet
  5. Excessive accumulation of metabolic waste products, as in conditions such as gout
  6. Unbalanced and unharmonious lifestyle and misuse of the body-mind apparatus, leading to the accumulation of toxic products, e.g. inadequate sleep, intense physical activity after food, excessive or wrongly timed mental or sexual activities, failure to adapt to the rhythms of nature
  7. Mental impurities, as described above
  8. Direct intake of toxins, e.g. addictive substances.

The practice of nadi shodhana pranayama will help to clear the accumulated pranic blockages, purifying the nadis.

Signs of purification

The signs of purification of the nadis are the same as the indicators of balance in the three doshas. Symptoms of physical disorder or disease disappear and there is a feeling of lightness in the body and the mind. Excessive fat and mucus disappear, indicating balance in kapha, stability and firmness in the body and mind become noticeable with balance in vata, and the internal organs, especially the digestive system and the intellect, start functioning efficiently when pitta is balanced. The urge to eat lessens, excretion is regular and efficient, the voice becomes deeper, steadier and sweeter, the need for sleep is reduced, and the quality of thoughts and meditation improve. The Hatha Yoga Pradipika (2:19-20) says that when the nadis are purified, the body becomes thin and glows, the digestive power increases, the inner sound or nada awakens and one becomes free from disease.

Research report

Nadi shodhana pranayama is one of the most necessary practices on the path of yoga. Due to its various stages and ratios of inhalation to exhalation, it is also suitable for most people. Keeping this in mind, the Yoga Research Foundation (YRF) undertook a research project from January to June 2002 to study some of the basic psychophysiological effects of nadi shodhana pranayama on 22 students enrolled in the Sannyasa Training Course at the Bihar School of Yoga (BSY). The research report is presented here.


Regular practice of nadi shodhana pranayama will:

  1. Improve the speed of performing repetitive mathematical tasks accurately
  2. Increase breath holding time (BHT)
  3. Increase peak expiratory flow rate (PEFR),
  4. Normalize pulse rate (P) and set it at a reduced normal value
  5. Normalize systolic and diastolic blood pressure (SBP & DBP) and set them at reduced normal values
  6. Balance the swara
  7. Stimulate ajna and mooladhara chakras.

Method of study

The experiment was designed on a pre-post basis, i.e. selected parameters were studied serially, and were measured both before and after particular phases of practice.

Measurement of parameters: The readings were taken at different phases of the study, namely:

  1. Pre: At the start of the study, before starting regular pranayama practice
  2. Pre 1:1: On achieving a count of 10 in inhalation and 10 in exhalation (10:10)
  3. Post 1:1: At the end of one month of regular daily practice of 10 rounds with a count of 10:10
  4. Pre 1:2: On achieving a count of 10 in inhalation and 20 in exhalation (10:20)
  5. Post 1:2: At the end of one month of regular daily practice of 10 rounds with a count of 10:20, at the end of the study.

Data for some parameters were collected before and after the practice of 10 rounds of nadi shodhana at each data collection, in a total of 10 readings.

Parameters: The parameters studied were:

  • 1. Speed and proficiency in repetitive mathematical tasks using a mental fatigue test, x 2 readings; the number of correct answers in the last 6 minutes of the 30-minute test was taken as the score of speed and proficiency
  • 2. Breath holding time (BHT) after deep inhalation, measured in seconds, x 5 readings
  • 3. Peak expiratory flow rate (PEFR) measured in litres per minute, using a PEFR metre; x 5 readings
  • 4. Pulse rate (P) taken per minute, using an electronic measuring device; x 10 readings
  • 5. Systolic blood pressure (SBP) in mmHg, using an electronic measuring device; x 10 readings
  • 6. Diastolic blood pressure (DBP) in mmHg, using an electronic measuring device; x 10 readings
  • 7. & 8. Occurrence of balanced swara directly after the practice, and pranic experiences at either ajna or mooladhara chakras during or just after the practice were registered in a practice diary. It was completed daily during the two one-month periods the students were practicing nadi shodhana pranayama with the count of 10:10 and 10:20 respectively.

Duration of study: Six months, from January to June 2002.

Sample: It consisted of 22 Sannyasa Training Course students of Bihar School of Yoga staying in the ashram from July 2001 to July 2002. There were 10 females and 12 males within the age range of 19 to 62 years. The mean age was 31.5, and only 4 students were older than 35 years. None had any major systemic medical problem. They were mainly students by occupation.

Procedure: After collecting the pre readings of all the parameters, a training class in nadi shodhana pranayama was conducted daily for five days. On reaching the count of 10:10, the subject reported for data collection and pre 1:1 readings were collected. The subject was then asked to continue with the daily practice of 10 rounds of nadi shodhana using the same count for a month, and to fill in daily a questionnaire regarding the experience of the practice. After one month the subject reported for data collection for post 1:1 readings and was then requested to gradually build the count to 10:20.

On reaching the count of 10:20, pre 1:2 readings were collected. The subject was then asked, as before, to continue with the daily practice of 10 rounds of nadi shodhana using that count and to fill in daily a questionnaire regarding the experience of the practice. After one month the subject reported for data collection for post 1:2 readings. This marked the end of the study, and the final readings of all the parameters were collected.

For each parameter the mean was calculated for the whole group. The mean values were also calculated separately for females and males to study gender difference, and separately for different age groups to study the influence of age. The group was divided into three age groups: group one, less than 25 years of age (6 students), group two, between 25 and 35 years of age (12 students) and group three, above 35 years of age (4 students).

Results and discussion

The mental ability to concentrate and maintain concentration without mental fatigue, or the attention span, was tested using a mental fatigue test. The results of the mental fatigue test for performance speed and proficiency have been summarized in Table 1.

The results show that the mean value of performance speed and proficiencyincreased in the group as a whole. The male subjects improved immensely while the female subjects showed a slight deterioration. The younger group showed significant improvement while the middle and the older groups showed marginal improvements.

Table 1: Results on Speed and Proficiency in Mental Tasks using the Mental Fatigue Test
  Pre Post
  Whole Group
(N=22) 139.48 147.5
  Gender Specific
F (N=10) 122.7 116.7
M (N=12) 154.73 178.9
  Age Specific
<25 (N=6) 97.33 125.67
25-35 (N=12) 167.82 170
>35 (N=4) 124.75 125.5

The measured effects on the respiratory system have been summarized in Table 2.

Breath holding time (BHT) indicates the health of the cardiac and respiratory systems as a unit. BHT for the whole group showed a continued improvement, but in the early phases it was greater than in the later phases. In women the improvement was slower but steadier than in men. Theolder age group showed more benefit throughout the experiment compared to the middle and younger age groups.

It is expected that in the older age group the vascular system would have blockages to a greater or lesser degree in the form of arteriosclerosis. The purifying action of nadi shodhana pranayama is likely to have a beneficial effect on the circulatory system, leading to an improvement in BHT. In the younger and middle groups the cardiac and respiratory systems may have been in optimal condition to start with and so BHT may have failed to show much improvement.

Table 2: Mean BHT and PEFR
  Pre Pre 1:1 Post 1:1 Pre 1:2 Post 1:2
(N=22) Whole Group
  49 54.91 59 58 61.45
  373.18 452.73 447.73 465 458.64
  Gender Specific
F (N=10) 40.5 43.2 44.4 45.1 50.8
M (N=12) 56.08 64.67 71.17 68.75 70.33
F (N=10) 315 351.5 355 347 359
M (N=12) 421.67 537.08 525 563.33 541.67
  Pre Pre 1:1 Post 1:1 Pre 1:2 Post 1:2
  Age Specific
<25 (N=6) 46.5 52.33 56.67 51.67 58.17
25-35 (N=12) 47.33 52.5 55.67 54.58 58.67
>35 (N=4) 57.75 66 72.5 77.75 74.75
<25 (N=6) 363.33 465.83 435 463.33 498.33
25-35 (N=12) 4.9.17 469.58 499.18 500.83 488.33
>35 (N=4) 280 382.5 312.5 360 310

Peak expiratory flow rate (PEFR) denotes the force of exhalation. It is an expression of effort by the respiratory muscles and the state of relaxation/constriction of the bronchial tree. The latter is influenced by the autonomic nervous system. PEFR is higher when the bronchi are relaxed, dilated and the respiratory system is working efficiently. The study showed improvement throughout, but in the early phases it was greater than in later phases. The trend was similar in men and women, but the magnitude was double in men than that in women. The younger group benefited much more throughout all the phases. The middle group benefited initially and then became steady. The benefit to the older group was fluctuating and to a much lesser degree.

The measured effects on the cardiovascular system have been summarized in Table 3. Pulse rate, SBP and DBP remained within normal limits throughout the experiment.

During the initial training phase the pulse rate increased and remained so until the end of the 1:1 ratio phase. At the onset of the 1:2 ratio phase it started reducing, and at the end of that phase it approached the pre nadi shodhana pranayama level. The pattern was similar in both gender groups, and the age specific changes were not remarkable. The immediate effect of the practice was to reduce the rate in the older group and elevate it marginally in the younger and middle groups.

Overall there was a stronger parasympathetic effect during the 1:2 ratio phase than during the 1:1 ratio phase.

For systolic BP, like the pulse rate, the long term effect of the practice was that it increased during the early phase of training, but started declining steadily from the end of the 1:1 ratio phase. The immediate effect of the practice was to decrease SBP in the whole group as well as in all age and gender groups.

Diastolic BP showed very little change throughout the experiment and there was no detectable pattern of change. There was no gender or age specific pattern.

The overall effect on the cardiovascular system (CVS) was stimulation during early phases as subjects were trying to achieve a predetermined pattern of breathing. As their bodies adjusted to this pattern, balance developed within the autonomic nervous system. The pulse rate and BP had already come down due to other purificatory and balancing factors such as six months of regular lifestyle and simple ashram diet, asana and shatkarma, kirtan and the joy of satsang. Nadi shodhana pranayama is a balancing and not a calming or introverting practice. It will only reduce excessive sympathetic tone. It will neither suppress its normal tone nor stimulate parasympathetic tone. Hence in relaxed, healthy, young adults the practice did not further reduce pulse rate and BP. Men and the younger group showed more stability in the CVS. As all the subjects were healthy, CVS status did not alter much during the experiment. Nadi shodhana pranayama did not have any significant effect on the CVS in this group.

The effect of the pranayama on the swara and pranic experience at ajna and mooladhara chakras was studied using a practice diary. Out of 22 subjects, 11 maintained the diary on a regular basis.

The subjects checked their swara, the flow of breath in both nostrils, before and after the practice. Among 11 subjects the total occurrence of balanced swara after nadi shodhana pranayama was 19.11%. To simplify we can say that for 19.11% of the practice time each person had a balanced swara.

The subjects noted down their pranic experiences at ajna and mooladhara chakras during and after the practice. Pranic experience at ajna chakra was found to occur frequently and at mooladhara chakra less often. Among 11 subjects, the total occurrence of pranic experiences at ajna was 70.83% of the practice time and at mooladhara it was 25.3% of the practice time for each person.


The results of this study support the conclusion that for generally healthy people the regular practice of nadi shodhana pranayama with a count of 10:10 x 10 rounds and a count of 10:20 x 10 rounds will:

  1. Increase speed and proficiency in repetitive mathematical tasks significantly at p value 0.01
  2. Increase BHT significantly at p value 0.003
  3. Increase PEFR significantly at p value 0.001
  4. Maintain normal pulse rate within normal value but not decrease it
  5. Reduce SBP as an immediate effect of practice significantly at p value 0.00015
  6. Maintain normal SBP and DBP at normal values without decreasing them as a long term effect
  7. Bring a balance in swara significantly
  8. Generate pranic experience at ajna and mooladhara chakras significantly.

This study examined some of the basic psychophysiological effects of nadi shodhana pranayama in a young healthy population. It showed that nadi shodhana pranayama does not excite or depress CVS in spite of the stress of a drastically low respiratory rate, about 2/min for 10 minutes, in the case of 10:20 ratio for 10 rounds. It has a beneficial effect on the respiratory function and improves the ability to stay focused during difficult mental tasks. It stimulates ajna and mooladhara chakras and balances ida and pingala nadis, thus enhancing spiritual progress.

Table 3: Mean Pulse Rate, Systolic and Diastolic Blood Pressure
  Pre Pre 1:1 Post 1:1 Pre 1:1 Post 1:1
(N=22) Pre Post Pre Post Pre Post Pre Post Pre Post
Pulse Rate 73.05 76.23 80.82 81 80.64 81.82 77.73 77.59 73.5 73.5
Systolic BP 116.59 113.36 123.73 121.23 120.64 116.23 119.41 113.41 118.59 117.59
Diastolic BP 76.68 78.05 78.95 79.45 77.64 77 78.91 75.73 76.27 78.86