Breath is life - but we know very little about it. Do you know that you use only ONE nostril at a time for breathing? At any time, either only the right or left nostril will be working. Place a finger half an inch below your left nostril for a few seconds, and then under your right. What did you notice? And now, for more. Do you know the active nostril changes, at regular intervals (approximately every one and a half hours) during the day? And that for a short period, both nostrils come into play?
The ancient practitioners of Hatha Yoga in India knew all this - and much more. They knew the intimate connection between breath and mind. For example, when you are angry, watch your breathing. It will be disturbed. And similarly, if you hold your breath for long, your mind will get agitated. The yogis were trying to get some degree of control over the mind. Since it is very subtle and impossible to grasp, they figured they could control it via the breath. They used the intimate connection between the breath and the mind - by controlling the breath, they were indirectly able to influence the mind.
There is a lovely fable of a minister punished by a king with imprisonment in a tower. He called his faithful wife to help him to escape, telling her to get a beetle, two drops of honey, a ball of slender and fine thread, a long twine and a long rope. The bewildered wife arrived with these things. He told her to moisten the antennae of the beetle with the honey, tie the thread to its body and leave it at the bottom of the tower wall. Smelling the honey ahead, the beetle slowly crept up the wall until it reached the minister. He then got hold of the end of the thread and asked his wife to tie the twine to the other end. He then pulled up the twine, and then the rope - using which he escaped. The idea is how to manage the links between the gross (rope, body) to the subtle (thread, breath), to the very subtle (scent of honey, mind)
Pranayama or control/regulation of the life force is thus the fourth step in the ashtanga yoga system laid down by Patanjali. It comes after yama, niyama and asana, so it should be undertaken after these. Control of the body through posture is the first step; control of the breath is the second, which will eventually lead to the control of the prana or life force.
Pranayama is not as complicated as it is made out to be, but neither is it something that can be trifled with. The ancient Sanskrit texts state that Pranayama correctly done can cure all diseases, but wrongly done - will only invite the same diseases! Breathing is an automatic process controlled by the autonomic nervous system. We do not have any conscious control over it. Just think what a mess we make of the things we have conscious control on (e.g. food). Therefore we ought to exercise EXTREME CAUTION before trying to meddle with something that God thought it best to keep away from our hands. It is thus of utmost importance to learn pranayama from a proper teacher.
After having done the kriyas, particularly neti, and also the asanas, the body is now ready to receive the maximum benefit of pranayama.
The first thing to learn is sectional breathing. We breathe through three parts of the chest upper, middle and lower as well as the abdomen. We have first to learn how to breathe through each section individually before we can breathe through all of them.
- Sit in any comfortable pose and then lift both arms and bend them backwards at the elbow to touch your back below the shoulder blades. Now take a few deep breaths through the upper chest. You can feel this part working in this posture.
- Now place your hands on your side chest, just under the nipple. Take a few deep breaths through the middle chest.
- Now place your hands on the sides lower chest where the rib cage ends. Take a few deep breaths through the lower chest.
- Place one hand on the navel. Take a few deep abdominal breaths.
- Now try to take a "tidal breath" involving inhalation and exhalation through all these parts.
Practice the above for a few days. Now we proceed to "Nadi-shodhana" or purification of the nadis. This is a preliminary process to pranayama, recommended by none other than Shri Sankaracharya over a thousand years ago.
Preparation for Nadi Shodhana
- Block your right nostril with your thumb. Breathe in and out deeply and silently (but not forcefully) through your left nostril 4-5 times
- Repeat by blocking the left nostril and breathe in and out through the right nostril.
- Now block the right nostril, inhale through left. Now release the right nostril and breathe out through it, while simultaneously blocking the left nostril. Repeat this a few times.
- Repeat the above process reversing the nostrils, i.e. block left, inhale through right and then block right, inhale through left
Practice the above for at least a week. Now we can begin the actual nadi-shodhana.
Step 1 - Block right nostril, inhale through left. Block left, Release right, exhale through right
Step 2 - Inhale through right while left stays blocked
Step 3 - Release left, block right, exale through left
There must be no gaps between the three steps
Repeat steps 1-3, two to five times ONLY, according to capacity, three times a day at sunrise, noon and sunset. Midnight is also recommended but probably impractical. In a few months, your nadis (psychic channels) will be purified as per the texts. These exercises are harmless if followed as per the directions. You are now ready to learn pranayama from a teacher. Good luck!
You can read more on What is pranayama here
And about the benefits of Pranayama Based on research here