The name alternate nostril breathing is due to the fact that we alternate between the two nostrils when we do the breathing. Yogis believe that this exercise will clean and rejuvenate your vital channels of energy, thus the name nadi sodhana (purification of nadis or channels).
With this exercise, we breathe through only one nostril at a time. The logic behind this exercise is that normal breathing does alternate from one nostril to the other at various times during the day. In a healthy person the breath will alternate between nostrils about every two hours. Because most of us are not in optimum health, this time period varies considerably between people and further reduces our vitality. According to the yogis, when the breath continues to flow in one nostril for more than two hours, as it does with most of us, it will have an adverse effect on our health. If the right nostril is involved, the result is mental and nervous disturbance. If the left nostril is involved, the result is chronic fatigue and reduced brain function. The longer the flow of breath in one nostril, the more serious the illness will be.
The Scientific Confirmation of Alternate Nostril Breathing
Medical science has recently discovered the nasal cycle, something that was known by the yogis thousands of years ago.Scientists have recently found that we don't breathe equally with both nostrils, that one nostril is much easier to breathe through than the other at any particular time and that this alternates about every three hours. The yogis claim that the natural period is every two hours, but we must remember these studies were done on people who do not have an optimum health level.
Scientists also discovered that the nasal cycle corresponds with brain function. The electrical activity of the brain was found to be greater on the side opposite the less congested nostril. The right side of the brain controls creative activity, while the left side controls logical verbal activity. The research showed that when the left nostril was less obstructed, the right side of the brain was predominant. Test subjects were indeed found to do better on creative tests. Similarly when the right nostril was less obstructed the left side of the brain was predominant. Test subjects did better on verbal skills.