Meditation has a wide range of scientifically measurable effects. In 1988 Michael Murphy and Steven Donovan, of the Esalen Institute, published The Physical and Psychological Effects of Meditation and reported 1,253 scientific and literary studies on meditation going back to 1931. When they published a second edition in 1996, they had added about 400 more studies. During those eight years, they reported, growth in research had been "nothing short of spectacular," with investigations moving beyond the gross physiology to subtle changes in biochemistry and voluntary control of internal states. The studies don't all line up perfectly in support of meditation's effectiveness. They create debate and raise questions. But, that is the way of science in every area it explores.
It takes a lot of money and time to study anything at the level proper for professional publication. The amazing array of studies visible even in the table of contents of Murphy and Donovan's book tells a significant story. There could not be such a rich set of published studies had there not first been a long, persistent history of meditation's effects, felt outside of science, by people practicing a wide variety of meditative styles. Each study began with an intriguing suggestion springing out of direct experience.
Listing all that we now know or suspect happens during a natural style meditation would be daunting. So, here are some highlights that I enjoy:
Physiologically, the meditative function brings reduced tension, greater blood flow, reduced blood pressure, slower breathing, reduced consumption of oxygen (a measure of metabolic level), increased brain activity in the frequencies associated with relaxation and happiness (alpha and theta waves). Chemicals normally associated with stress (blood lactate and the hormone cortisol) are reduced, and calming hormones associated with wellbeing (melatonin and serotonin) are increased.
Indeed, meditation seems to be uniquely capable of processing the dangerously-common stress hormone, cortisol. One study showed declines of 25% in long-term meditators during their sittings. Short-term meditators showed small declines, and no change was seen in the control groups doing rest and relaxation (Murphy and Donovan 1996:65). Cortisol is an adrenal hormone that is found in extremely high levels in people with pain and is associated with the fight-or-flight response, that stress-readiness condition urgently needed during periods of acute physical danger. Cortisol is a damaging chemical to leave lingering in the bloodstream. It can be cleared out when the event that triggered it can be addressed directly with an explosion of physical action (fighting or running away); otherwise, it lingers and corrodes the body. Dharma Singh Khalsa, M.D., a previous graduate student of Benson and author of Meditation as Medicine says that the stress-induced overproduction of stimulating hormones, such as cortisol and adrenaline, "accelerates the aging process, and is a major risk factor not only in Alzheimer's disease but also in the far more common condition of age-associated memory disorder" (2001:84,180). He also favors meditation as a way of clearing cortisol from the bloodstream.
Herbert Benson, then at the Harvard Medical School, joined physiologist Robert Keith Wallace, Ph.D and others in the early 1970s in studying the physiology of people practicing TM. In 1975 he reported on this early research in the first of his several bestselling health and wellness books, The Relaxation Response. Benson saw that there was a coordinated deep restfulness during certain forms of meditation. Although people who meditate knew that the body can become unusually quiet, it was striking scientific news that meditation is producing significantly deeper rest than sleep. This is determined by measuring how much oxygen is consumed. In sleep, oxygen consumption gradually decreases about eight percent over four or five hours. In meditation, it drops 10 to 20 percent in the first three minutes (Benson 1975:64).
The amount of oxygen an animal consumes changes moment from moment, being controlled by a complex process of the body called metabolism. We can indirectly affect metabolism by changing the level of physical activity?resting, running, eating, sleeping, or meditating?but we cannot control it directly. We don't lower our oxygen consumption when holding the breath, because the tissues go right on consuming oxygen from the bloodstream according to their need and at approximately the same rate. So, this significant lowering of the consumption of oxygen in meditation implies a deep, complex, and organized shift in what the body is up to. It is especially significant considering that most meditators have no idea it is happening.
Benson's original work on oxygen consumption has held up well. In 1996 Murphy and Donovan reported that over 40 studies have shown reduction of oxygen and carbon dioxide elimination. They report that oxygen consumption has been reduced by 55% and carbon dioxide elimination by 50%, and that breath rates have been seen as low as one breath per minute.
Recalling the mapping of the Naturals in the first two talks (Chapters 6 and 7), we could predict that only some methods of meditation would produce these changes. And that is true. Citing 45 studies between 1957 and 1991, Murphy and Donovan observed that, "Such quieting of the organism, however, happens for the most part in quiet meditation of the TM or zazen type, not in active, high-arousal practices such as Ananda Marga Yoga" (1996:69). In my terms, it happens with the Naturals.
The Meditating Brain
Benson reported that certain electrical brain activity (EEG alpha and theta waves) increases both in intensity and frequency during meditation (1975:64). His early findings have held up well. Murphy and Donovan cite 36 studies between 1955 and 1987 showing increasing alpha rhythms using many types of meditation, including sessions with Zen masters (see EEG described in Chapter 9).
Murphy and Donovan cite 25 studies between 1955 and 1984 showing an unusual "synchronization/coherence" of alpha activity among the four quadrants of the brain, front, back, left, and right. They note that this effect has been scientifically associated with creativity. Synchronization of the various parts of the brain is particularly significant because meditation is more than relaxation and peacefulness. It opens the mind to a rich source of intelligence and creativity. In the next talk, I will describe recent research on the brainwave patterns in highly developed (enlightened) long-term meditators.
Our knowledge of the brain in meditation will become much richer in coming years as researchers move beyond EEG to new, dynamic, 3-dimensional imaging tools, such as computed tomography and magnetic resonance imaging. These tools have already been used to show how areas of the brain shift activity during meditation and to chart some lasting changes in brain structure with long meditation practice.
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