The overall rate at which the body consumes energy is called the metabolic rate. The more active we are, the more energy we use and the higher the metabolic rate. It is believed that there is a lower limit to metabolic activity - the basal metabolic rate, which is considered to be the minimum energy required to "tick" the body in the supine and sitting positions.
In the state of deep sleep, this rate can be 10% below the base level. If it falls even lower, for normal people it is already considered a deviation from the norm. Since oxygen is one of our main sources of energy, metabolic rate is reflected in the rhythm and depth of our breathing. When the early meditators found that their breathing was becoming very slow and shallow, they concluded that their metabolic rate had dropped significantly.
The first objective analysis of these changes was carried out in 1965 in London. Dr. John Allison, measuring the rate of breathing, found that instead of the usual twelve breaths per minute during meditation, six were recorded. This is rather slow breathing, although it cannot be considered a strong deviation from the norm. This pace can be achieved outside of meditation if you breathe deep enough. What is really unusual is that the meditator's six breaths were very shallow and barely perceptible.
The meditator did not compensate for slow breathing by inhaling more air; on the contrary, he inhaled significantly less air with each breath. The physiologist believed that this type of breathing corresponded to a decrease in metabolic activity to 75% of the normal level. Allison believed that anyone who breathed like this for twenty minutes should have died by any calculation. But the meditator is alive!
The decrease in oxygen consumption during Transcendental Meditation was confirmed in 1970 by Dr. Keith Wallace from America. He measured oxygen consumption directly and found an average reduction in oxygen consumption of 16%.
Wallace also studied some other physiological changes. He found that the amount of carbon dioxide decreased in proportion to the decrease in oxygen consumed. Thus, the body used less oxygen. This confirms that the reduced pressure is a consequence of the reduced oxygen demand.
This hypothesis is supported by two other observations. Firstly, there was no increased pressure after meditation, that is, the body did not need to compensate for the lack of oxygen. Second, measurements of dissolved gases in the blood showed normal levels of oxygen and carbon dioxide. When we are active, carbon dioxide levels rise and the body compensates for the increase in breathing rate and depth. When the level of carbon dioxide decreased, the respiratory rate decreased.
Wallace's observations showed that optimal levels of both gases were maintained during the TM period. The low rate and depth of respiration, therefore, must be the result of reduced metabolic activity. If they were the cause, there would be a lack of oxygen in the blood and accumulation of carbon dioxide.
But this difference usually went unnoticed, and many believed that a state of inner peace could be achieved by slowing down the breath, as in a state of rest and mental relaxation. Deliberately slowing down breathing will cause oxygen starvation and mild carbon dioxide poisoning of the brain, which can lead to a change in consciousness. But this, of course, is not the state that is achieved in the process of meditation.
It is important to understand that during meditation, neither the body nor the brain lacks oxygen. The oxygen entering the blood remains at its usual level: it’s just that the body’s needs are reduced.