Yoga has considered internal purification of the human body in depth. The shuddhi kriyas (Cleansing Processes mentioned in the Niyamas of the 8 Limbs of Yoga) are intended to help to achieve total purification of the body. The organs where there can be a lot of impurities require these shuddhi kriyas. The internal organs, which come into contact with the external matters regularly, need to be purified. The trachea regularly comes into contact with the external air, the food pipe comes into contact with the external food products, and the mind comes into contact with the thoughts of the external world; these and such other organs need to be purified internally. This is especially useful in today’s climate where there are many man-made chemicals that come into contact with our bodies and increase our toxic overload. Certain conditions can be cured with these kriyas, and the emphasis in Yoga is on the natural method of cleansing.

Most of these shuddhi kriyas are not meant to be practiced as part of the daily routine. When it is necessary to purify the body, these kriyas may be practised daily, but when the need is over, the practice is stopped. However a few are able to be continued for increased health and well-being.

According to Hatha Yoga Pradipika , there are six cleansing techniques called Shat Kriyas. They are Kapalabhati, Trataka, Neti, Dhouti, Nauli and Vasti.

Shat means ‘six’ and kriya means ‘cleansing’. Yogic kriya remove the waste materials of our internal organs which are not expelled normally. Therefore, the aims of Hatha Yoga and of the Shatkriyas are to cleanse the internal organs and thereby create harmony between the major pranic flows, Ida and pingala, and attaining physical and mental purification and balance.

The shatkriyas are also used to balance the three doshas or humours in the body; Kapha- the mucus, pitta- the bile and vata-the wind. According to both Ayurveda and Hatha Yoga an imbalance of the doshas will result in illness. These practices are also used before Pranayama and the other higher yoga practices in order to purify the body from toxins and to ensure safe and successful progression along the spiritual path.

Most of these powerful techniques should be taught by experienced people. It is essential to be instructed as to how and when to perform them according to individual needs.

1. Kapalabhati (Cleansing Breath) ‘Kapala’ in Sanskrit means skull; and ‘Bhati’ means shine. So the term ‘kapalabhati’ means an exercise that makes the skull shine. This kriya cleanses the skull. Kapalabhati is a breathing technique for purifying the frontal region of the brain. It cleanses the respiratory system and the nasal passage and removes the spasm in bronchial tubes. Carbon dioxide is eliminated on a large scale and impurities of the blood are thrown out. The tissues and the cells absorb a large quantity of oxygen. The practitioner keeps up good health. The heart functions properly and the circulatory and respiratory systems toned to a considerable degree.

2. Trataka (Eye Exercises) Trataka is fixing the mind by gazing steadily to an object (usually a candle) without winking. While doing the practice relaxation of the eyes is important. This practice activates the tear glands and there by purifies the visual system. It improves the eyesight, promotes good concentration and will power.

3. Jala Neti (Upper Nasal Cleansing) Jala Neti is intended for the purification of the nostrils. The nostrils must be kept clean. Unclean nostrils will lead to irregular breathing and cause all manner of problems. Neti are in four types namely; Jala Neti, Sutra Neti, Dugdha Neti (milk is used) and in Ghrita Neti ghee is used instead of water. Sutra Neti is different technique of nasal cleaning where a waxed thread or a thin soft rubber catheter is used. Neti kriya, in general purifies most structures in the head and neck. Neti kriya not only clears the nasal passage but also renders the nose resistant to many irritants.

4. Dhouti (Cleansing the intestine) Dhouti Kriyas are meant for cleansing the upper intestinal tract up to the stomach. There are three types of Dhouti; jala Dhouti or vamana Dhouti, vastra Dhouti and danda Dhouti. Jala Dhouti or Vaman Dhouti is cleansing the stomach with water. In this kriya the lukewarm salt water is drunk and vomited. In Vastra Dhouti cloth is used for cleansing the stomach. In danda Dhouti a rubber tube called ‘danda’ is used. In this technique saline water is drunk and taken out through the danda which is pushed into the stomach. Dhouti practices are highly useful for gastric trouble, acidity etc. It is good for asthma. Dhouti kriya activate the digestive fire and helps to have good appetite.

5. Nauli (Abdominal muscle and Viscera) Nauli is one of the important Kriyas to purify and strengthen the vital internal organs as a whole. It is a yogic technique of massaging the whole abdomen and stomach by contracting and rolling the abdominal muscles, especially the rectus abdominis muscle. The practice of Agnisara kriya and Uddiyana bandha are the preparatory practices for doing the Nauli. Naulis are three types:

Madhyama Nauli: - It is the technique of contraction and isolation of the rectus abdominus muscles at the center of the abdomen.

Vama Nauli: - It is the technique of contraction and isolation of the rectus abdominus muscles at the left side of the abdomen.

Dakshina Nauli: – It is the technique of contraction and isolation of the rectus abdominus at the right side of the abdomen.

Nauli Chalana: - When one has gained control over these types of Nauli, rolling of the recti muscles clockwise and anti-clockwise is practiced. This is called ‘Nauli Chalana’.

Nauli will be helpful in removing the digestive ailments. It is very useful in curing constipation. It reduces the obesity in the stomach region. The function of liver, spleen and other glands are activated by nauli. It increases the appetite. The people who are having high blood pressure, active ulcers or hernia complaints should not practice nauli.

6. Vasti (Cleaning of the Rectum) The word ‘Vasti’ is a general term pertaining to the lower abdomen, belly, pelvis and bladder. Vasti kriya is a Hatha Yoga process of yogic enema to clean the colon by sucking water through anus. The Vasti practices should be done in empty stomach in the early morning. Vasti is practiced in different ways.

Jala Vasti (Yogic enema with water):- In this technique the practitioner will be anus by practicing the Ashwini mudra. In other ways a rubber tube may be inserted into the anus. After sucking the water the same will be expelled through the anus.

Sthal Vasti (dry yogic enema):-This technique may be done, sucking the air into the bowels, by performing Ashwini mudra. Then holding for sometime and expel it through the anus.

Vasti cleans the colon by removing the gas and other accumulated waste material from the colon. Vasti helps in curing stomach ailments, increase appetite, cure for constipation. Body becomes light and active. It helps to cool down the body heat of the advanced practitioner of Pranayama.