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diminished. The lungs are not out of order, but the carbon dioxide concentration of the brain tissues is too low to allow a deeper respiratory process. Nature, it seems, has provided for carbon dioxide storage in the brain in order to activate the respiratory drive and make the oxygen consumption process more efficient. Kumbhaka restores the levels of carbon dioxide in the brain tissues, allowing the system to fully extract oxygen. Additionally, when carbon dioxide is retained in the brain, it increases the capacity for assimilating ions.
Increased carbon dioxide levels in the blood can lead to altered states of consciousness and feelings of expansiveness. It is interesting that researcher J. Wolpe (Psychotherapy by Reciprocal Inhibition, Stanford University Press, 1958) recommended what is called CO2 therapy. He suggested the administration of 65 percent carbon dioxide and 35 percent oxygen for treatment of anxiety based on his experiments, which indicated that one to four of such inhalations will reduce anxiety for several hours or in some cases, for weeks. In another experiment, there were three control groups of highly anxious subjects. One inhaled a carbon dioxide mixture, the second hyperventilated and the third inhaled only air. The anxiety levels became significantly lower in the first group. They also showed a trend toward reduced anxiety after a 24-hour period, not found in the other two groups.
Kumbhaka, in this light, may be called a self-administered CO2 therapy. However, its effect is beneficial up to a certain optimum level only. Beyond this, it becomes distinctly harmful and may even cause disorientation and hallucination. Hence, it is always stressed that the practice of kumbhaka must be undertaken only under the guidance of an experienced teacher. Metabolic levels and brain activity must be adjusted to produce optimum conditions; only then it will become beneficial.
Another aspect of kumbhaka is that it trains one to control the part of the brain ruling the involuntary processes. One can move the hands, but not the hypothalamus. However, through
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