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The Metabolic and Respiratory Systems
According to most contemplative teachings, the turbulence and distress of ordinary life can be reduced through quiet meditation. The subtle turnings of the mind's substance, the citta-vritti as they are described in Patanjali's Yoga Sutras, can be quieted so that a clearer and deeper apprehension of inner and outer worlds might ensue. This quieting also results in a growing efficiency of mind and body and a concomitant reduction in the organism's consumption of energy. This picture of contemplative transformation, embedded in Hindu, Buddhist, Taoist, and other teachings, corresponds to the one we find in contemporary studies of meditation's effects on breathing. Some forty studies have shown that oxygen consumption is reduced during meditation, that carbon dioxide elimination and respiration rate are reduced, and that minute volume is lowered. Other studies, moreover, have shown that oxygen consumption was decreased in subjects working at a fixed intensity, and that meditators sometimes suspend breathing longer than control subjects without apparent ill effects. These studies strongly suggest that meditation lowers the body's need for energy and the oxygen to help metabolize it. 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.
Various studies have shown that oxygen consumption is reduced during meditation (in some cases up to 55%), that carbon dioxide elimination is reduced (in some cases up to 50%), that respiration rate is lessened (in some cases to one breath per minute when twelve to fourteen breaths per minute are normal), and that minute volume is also lowered. See Sudsuang et al. (1991), Kesterson (1986), Wolkove et al. (1984), Morse et al. (1984), Singh (1984), Cadarette et al. (1982), Hoffman et al. (1981b), Jevning et al. (1978c), Fenwick et al. (1977), Peters et al. (1977a, 1977b), Benson et al. (1977a), Dhanaraj and Singh (1977), Elson et al. (1977), McDonagh and Egenes (1977), Corey (1977), Routt (1977), Davidson (1976), Benson et al. (1975c), Glueck and Stroebel (1975), Woolfolk (1975), Beary and Benson (1974), Hirai (1974), Parulkar et al. (1974), Benson et al. (1974a), Kanellakos and Lukas (1974), Benson et al. (1973a), Banquet (1973), Treichel et al. (1973), Wallace and Benson (1972), Russell (1972), Watanabe et al. (1972), Goyeche et al. (1972), Wallace et al. (1971b), Wallace (1971), Allison (1970), Sugi and Akutsu (1968), Karambelkar et al. (1968), Kasamatsu and Hirai (1963, 1966), Anand et al. (1961a), Wenger and Bagchi (1961), Anand and Chhina (1961), and Bagchi and Wenger (1957).
Badawi et al. (1984) observed fifty-two periods of spontaneous respiratory suspension in eighteen subjects during the practice of TM. These periods were correlated with subjective experiences of pure consciousness. Total EEG coherence showed a significant increase during these periods, moreover. Earlier, Farrow and Hebert (1982) observed, over four independent experiments, asignificant number of episodes of breath suspension in forty subjects practicing TM, where the frequency and length of the suspension were significantly greater than for control subjects relaxing with eyes closed. This verified a previous study performed by Hebert (1977).
Benson et al. (1978a) reported that oxygen consumption was decreased by 4% in eight subjects working at a fixed intensity (on an electrically braked stationary bicycle ergometer) when the relaxation response was simultaneously elicited.
Vakil (1950) reported the case of a middle-aged yogi who meditated for fifty-six hours in an airtight concrete cubicle, measuring approximately five feet by five feet by eight feet and lined with thousands of three-inch rusty nails. The cubicle was then filled with 1,400 gallons of water through a narrow opening bored in the lid, then resealed, and the yogi remained immersed for an additional seven hours. The author examined the yogi immediately on his removal, and found his pulse, blood pressure, and respirations normal.
Though it seems clear that meditation produces changes in breathing patterns, a number of studies have found little difference in various metabolic measurements between meditation and other self-regulation strategies. D.H. Shapiro (1982) argued that "the original belief that we would be able to discriminate meditation as a unique physiological state has not been confirmed —on either an autonomic or a metabolic level or in terms of EEG pattern." Puente (1981) compared forty-seven volunteers randomly assigned to TM, Benson's relaxation response, or no treatment, and found that none of the techniques exhibited clear superiority in reducing physiological arousal (measured by respiration rate, heart rate, electromyogram, electroencephalogram, and skin conductance). A similar experiment using TM meditators of varying experience indicated that individuals with 1.5 years of experience exhibited arousal levels similar to individuals with over five years of experience [also see Puente and Bieman (1980)]. Morse et al. (1977) concluded that relaxation, meditation, and relaxation hypnosis yield similar results, all suggestive of deep relaxation. In The Relaxation Response (1975), Benson argued that the physiological response pattern found in meditation was not unique to meditation but common to any passive relaxation strategy. See also Boswell and Murray (1979), Cauthen and Prymak (1977), and Fenwick et al. (1977), Travis et al. (1976), Curtis and Wessberg (1975-76), and Walrath and Hamilton (1975).
Recently, Jevning and O'Halloran (1984) summarized the results of their own and others' studies on the metabolic characteristics of TM and its relationship to sleep and unstylized eyes-closed rest/relaxation. They concluded that:
We have seen, in the course of research into these questions, a clearer delineation of the differences and similarities between TM and other hypometabolic states as more sophisticated studies involving more clearly specified subject groups and more powerful measures have been applied. At present, it seems unlikely that TM is sleep or that it is the same as simple eyes-closed rest. Whether physiological changes accompanying TM might be induced by other stylized means is at present a moot and, in our opinion, a probably unproductive question, in view of the dearth of regularly practiced techniques. The noncultic relaxation response advocated by Benson et al. (1974b), may deserve further investigation in this regard.
Recently, Jevning et al. (1992) conducted a review of the physiology of meditation, with emphasis on research in which the TM technique was used. They state that:
Although facts therefore support the relevance of physiology to meditation (and indeed, meditation to physiology), the precise relationship of physiology to the unique subjectivity of meditation remains a primary research question.
Muscle Tension
Muscle tension, like oxygen consumption, has been reduced during recent experiments involving quiet meditation. In the secure calm of meditation, it seems, one comes to feel less need for defensive armoring. One can begin to relax more deeply as conditioned expectations of threat diminish. Such relaxation of the musculature contributes to the body's lowered need for energy, the slowing of respiration, and the lowering of stress-related hormones in the blood.
Credido (1982) tried to find whether a low-arousal relaxation pattern consisting of frontalis EMG decreases and peripheral skin temperature increases could be attained more effectively through biofeedback or meditation training. Thirty female subjects, ranging in age from twenty-one to fifty-nine, were randomly assigned to a patterned biofeedback group, a clinically standardized meditation group, or a control group, and were seen weekly for seven sessions. The meditation group showed significantly lower EMG levels than the other groups. No group had significant temperature increases. The biofeedback group had difficulty patterning the two feedback signals simultaneously, confirming the difficulty revealed by other studies in training individuals to gain voluntary control over more than one physiological modality with biofeedback.
Zaichkowsky and Kamen (1978) studied forty-eight subjects to determine whether EMG biofeedback, TM, or Benson's relaxation response produced decreased muscle tension. They found that all three groups had significant decreases in frontalis muscle tension when compared with a control group. Morse et al. (1977) monitored respiratory rate, pulse rate, blood pressure, skin resistance, EEG activity, and muscle tension for forty-eight subjects divided equally into meditation, hypnosis, relaxation, and control groups. Their results showed significantly better relaxation responses for those practicing a relaxation technique than the control group. There were no significant differences between the relaxation techniques, however, except for the measure of muscle tension, in which meditation was significantly better. Others reporting significantly reduced muscle tension through meditation include Delmonte (1984f), Brandon (1983), Bhalla (1981), Cangelosi (1981), Delmonte (1979), Kemmerling (1978), Miller et al. (1978), Fee and Giordano (1978), Pelletier and Peper (1977b), Haynes et al. (1975), Ikegami (1974), Gellhorn and Kiely (1972), and Das and Gastaut (1955).
Ikegami (1974) compared muscle tension in the lotus position with other relaxed forms of sitting, and found that it was lower than in any other posture except that of lying down.
Citing the work of Cauthen and Prymak (1977), Curtis and Wessberg (1975-1976), and Travis et al. (1976), D.H. Shapiro (1982) pointed out that "most studies have found that the constellation of changes is significantly different between meditation groups and placebo control groups but not between meditation and other self-regulation strategies."
Skin Resistance and Spontaneous GSR
Low skin resistance, as measured by the galvanic skin response test, is generally thought to be a reliable indicator of stress because it is caused in large part by anxiety-induced perspiration. Like respiration rate and muscular tension, it has been affected by meditation in many contemporary experiments. This measure of stress, we believe, fits into the general picture from both traditional and modern accounts that meditation often lowers anxiety.
Increased skin resistance, as well as lower frequency of spontaneous galvanic skin responses, has been widely reported in the TM literature or in studies of TM groups [see Delmonte (1984c), Bono (1984), Bagga and Gandhi (1983), Orme-Johnson and Farrow (1977), Farrow (1977), Laurie (1977), West (1977), T.R. Smith (1977), Orme-Johnson (1973), Wallace and Benson (1972), Wallace et al. (1971b), and Wallace (1971)]. Other researchers who concluded that meditation increases skin resistance (and sometimes lowers the frequency of spontaneous GSR fluctuations) are: Schwartz et al. (1978), Sinha et al. (1978), Pelletier and Peper (1977a), Glueck and Stroebel (1975), Walrath and Hamilton (1975), Woolfolk (1975), Benson et al. (1973a), Akishige 1970), Akishige (1968), Karambelkar et al. (1968), and Bagchi and Wenger (1957). In addition to increased skin resistance, Wenger and Bagchi (1961) found slow oscillatory skin-resistance waves in the later part of meditation for several subjects.
In reviewing studies of meditation's effect on GSR, Shapiro (1982) said that early first-round studies suggested that skin resistance significantly increased for subjects in Transcendental Meditation groups compared with control groups, but cited more recent studies showing no significant differences in GSR between meditation and other self-regulation strategies, including self-hypnosis, progressive relaxation, and other modes of instructional relaxation [see Lintel (1980), Boswell and Murray (1979), Parker et al. (1978), Morse et al. (1977), Cauthen and Prymak (1977), Travis et al. (1976), Curtis and Wessberg (1975), and Walrath and Hamilton (1975)].
Other Physiological Effects
Brain Metabolism
Using positron emission tomography, measurements of the regional cerebral metabolic rate of glucose are able to delineate cerebral metabolic responses to external or mental stimulation. Using data from PET scans performed in eight members of a yoga meditation group, Herzog et al. (1990-1991) showed the ratios of frontal vs. occipital rCMRGlc were significantly elevated indicating a holistic behavior of the brain metabolism during yogic meditation vs. a normal control state.
Salivary Changes
Morse et al. (1983) studied ten dental patients requiring nonsurgical endodontic therapy on upper anterior teeth who practiced simple word meditation in order to relax. Results showed significant pretest/posttest-meditation anxiety reduction measured by questionnaire, increased salivary volume, reduced salivary protein, increased amylase, and increased salivary pH.
Earlier, Morse et al. (1982) tested the hypothesis that salivary changes from stress to relaxation will be from opaque to translucent and from high to low protein levels, and that salivary bacteria will increase under the condition of stress and decrease under the condition of relaxation. Stress and relaxation of their twelve subjects, all dental students, were evaluated before and after meditation by verbal reports and examination of saliva for opacity, translucency, protein, and bacteria (resazurin dye method). Subjects were taught word meditation and instructed to meditate twice daily for twenty minutes. The study began one week after the subjects learned meditation and continued for six weeks. There were significant anxiety-reduction changes by the end of the meditation sessions as measured by increased salivary translucency, decreased salivary protein, and reduced subjective evaluation of stress. In addition, bacteria levels showed a significant decrease by the end of the meditation sessions. The results support previous findings by Morse in regard to salivary changes as measures of stress reduction mediated by meditation [see Morse et al. (1977, 1981), Morse (1976b, 1977a), and Morse and Hildebrand (1976)]. The finding of higher bacteria levels under stress and lower bacterial levels under relaxation indicates that stress may contribute to dental caries and relaxation may have an anticaries effect.
McCuaig (1974) studied one male TM practitioner with six months of experience during ten sessions over a two-week period and found that meditation produced a general increase in salivary minerals, especially sodium, 70%; magnesium, 42%; calcium, 36%; inorganic phosphate, 46%; and potassium, 23%. Salivary zinc was not significantly altered. Protein content of the saliva was increased during meditation by 60%. McCuaig stated that salivary changes during TM indicate that extracellular fluid electrolytes may also be altered during this state. Some of the increase in solids is undoubtedly due to water reabsorption and/or the secretion of a more concentrated saliva. According to McCuaig, however, the large difference in the degree of concentration of solids indicates more than an overall change in water concentration. Differing increases in acid-soluble over acid-insoluble protein, moreover, and the fact that the former is decreased ten minutes after meditation while the latter remains elevated, indicate a specific process involving these substances.
Effectiveness in the Treatment of Disease
Meditation has been found to be of benefit in several conditions that may have a mental component to their etiology.
Premenstrual syndrome (PMS) is a disorder for which there is no known cause or consistent treatment. Possible etiological factors include endocrinologic imbalances, dietary deficiencies, and excessive psychological stress. Goodale et al. (1990) found an improvement in physical and emotional symptoms after elicitation of the relaxation response over a five-month period. A suggested mechanism of action was reduction in norepinephrine receptor sensitivity.
Cerpa (1989) found the blood sugar levels of subjects with type II diabetes practicing a meditation-relaxation technique (CSM) were significantly reduced after participating in a six-week program, whereas the blood sugar levels of subjects in a diabetes education program and a control group did not significantly change, indicating meditation-relaxation techniques could be of significant benefit in diabetes control. Contrary to predictions, the state and trait anxiety levels of the three groups remained relatively constant.
A number of studies have concluded that meditation is useful in the treatment of asthma. See: Gong et al. (1986), Goyeche et al. (1982), Corey (1977), and Honsberger and Wilson (1973a, 1973b).
Gaston et al. (1988-1989) found that meditation may be clinically effective for some patients in reducing their psoriasis symptoms.
In a preliminary study, Kaplan et al. (1993) found evidence suggesting a meditation-based stress reduction program is effective for patients with fibromyalgia, a chronic illness characterized by widespread pain, fatigue, sleep disturbance, and resistance to treatment.
Hershfield et al. (1993) found enough evidence of improvement in a pilot study of Crohn's disease patients using meditation to warrant a control study.
Treatment of Cancer
Magarey (1981b, 1983) stated that medical technology has not reduced the death rate from cancer for fifty years, and suggested that a broader, holistic approach involving meditation was needed. He pointed out that meditation is associated with physiological rest and stability, and also with the reduction of psychological stress and the development of a more positive attitude to life, with an inner sense of calmness, strength, and fulfillment.
Meares proposed a form of intensive meditation associated with the regression of cancer (1983); discussed the relationship between stress, meditation, and cancer (1982a, 1982b); reported on a case of regression of recurrence of carcinoma of the breast at a mastectomy site associated with intensive meditation (1981); reported the results of treatment of seventy-three patients with advanced cancer who attended at least twenty sessions of meditation and experienced significant reductions of anxiety and depression (1980a); reported on a case of remission of massive metastasis from undifferentiated carcinoma of the lung associated with intensive meditation (1980b); analyzed meditation as a psychological approach to cancer treatment (1979b); reported on a case of regression of cancer of the rectum after intensive meditation (1979a); analyzed the quality of meditation effective in the regression of cancer (1978a); reported on the regression of osteogenic sarcoma metastases associated with intensive meditation (1978c); looked at the relationship between vivid visualization and dim visual awareness in the regression of cancer after meditation (1978a); raised the issue of atavistic regression, which reportedly occurs in meditation, as a factor in the remission of cancer (1977); and reported on the case of a woman whose breast cancer was alleviated through intensive meditation (1976a).
Gersten (1978) reported the case of a forty-three-year-old patient who used meditation as a treatment of last resort for diplopia and ataxia. Although the reasons for the improvement his patient experienced in these diseases is elusive, Gersten believed that meditation was a significant factor in the healing process. Pelletier (1977b) reported the successful use of meditation and visualization with cancer patients.
Changes in Body Temperature
Studies by Herbert Benson, Elmer Green, and others have shown that Tibetan monks and Indian yogis can raise the temperature of their fingers and toes at will, confirming many written and verbal reports that spiritual adepts often achieve exceptional control of their bodies. A wide range of physiological functions has been brought under some degree of self-control in meditation experiments, showing that traditional accounts have been accurate in this regard.
Benson et al. (1982a) reported that three practitioners of the advanced Tibetan Buddhist meditational practice known as g Tum-mo (heat) yoga exhibited the capacity to increase the temperature of their fingers and toes by as much as 8.3°C.
Alleviation of Pain
Kabat-Zinn et al. (1987) studied 225 patients in chronic pain following training in mindfulness meditation. Large and significant overall physical and psychological improvements were recorded with the Pain Rating Index (PRI), measures of negative body image (BPPA), number of medical symptoms (MSCL), and global psychology symptomatology (GSI). Earlier, Kabat-Zinn et al. (1985) trained ninety chronic-pain patients in mindfulness meditation. Statistically significant reductions were observed in measures of present-moment pain; negative body image; and inhibition of activity by pain, symptoms, mood disturbance, and psychological symptomatology, including anxiety and depression. Pain-related drug utilization decreased and activity levels and feelings of self-esteem increased. Improvement appeared to be independent of gender, source of referral, and type of pain. A comparison group of patients in pain did not show significant improvement on these measures after traditional treatment protocols. Still earlier, Kabat-Zinn (1982) presented data on fifty-one chronic-pain patients who had not improved with traditional medical care. The patients experienced low-back, neck, shoulder, and headache pain. Some also experienced facial, angina pectoris, noncoronary chest, and gastrointestinal pain. After practicing mindfulness meditation for ten weeks, 65% of the patients felt less pain [see also Kabat-Zinn et al. (1984b) and Kabat-Zinn and Burney (1981)].
Hustad and Carnes (1988) showed the effectiveness of walking meditation in reductions of EMG readings, muscle tone, and levels of pain and/or anxiety. Mills and Farrow (1981) found that TM increased pain tolerance and reduced distress, while the physiological response to pain remained unchanged. Pelletier and Peper (1977b) studied three adept meditators who voluntarily inserted steel needles into their bodies while such physiological measures as EEG, EMG, GSR, EKG, and respiration were recorded. Although each adept used a different passive attention technique, none reported pain. Lovell-Smith (1985) reported three cases in which TM was successful in reducing migraine headache pain. Buckler (1976) found that TM was effective in relieving muscle-tension pain. Morse et al. (1984), Katcher et al. (1984), Morse et al. (1984c), Morse et al. (1981), Morse and Wilcko (1979), Morse (1977), and Morse (1976b) reported that meditation-hypnosis relieved pain and anxiety during nonsurgical endodontic therapy. Mandle et al. (1990) reported significant reduction in anxiety and pain in patients in which the relaxation response was elicited prior to femoral angiography. Goleman (1976) described an individual, who had not been helped by a wide variety of medical treatments, whose migraine headaches disappeared three days after beginning meditation. Anderson (1984) reported that meditation was used successfully in the treatment of primary dysmenorrhea among sixty-eight women. Benson et al. (1974b) and Benson et al. (1973a) reported that TM was effective in decreasing headache pain. See also Sharma et al. (1990), Fentress et al. (1986), Benson et al. (1984), and Kutz et al. (1983).
Exceptional Body Control
Kabat-Zinn and Beall (1987) and Kabat-Zinn et al. (1984) reported on a mental training program based on mindfulness meditation to optimize performance in collegiate and olympic rowers.
Bono (1984) studied sixteen beginning practitioners of Transcendental Meditation, nine meditators with five years of practice, and twenty control subjects who sat quietly with eyes closed for twenty minutes. He found a slight relationship between meditation and aptitude for changing heart rate, no appreciable difference between groups for changes in skin conductance, and no appreciable differences between groups in their ability to modify spontaneous electrodermal responses. However, the long-term meditators were significantly better than controls in their ability to control phasic electrodermal responses. The author concluded that the meditation groups tended to be slightly better than controls at operant autonomic learning.
A number of researchers have stated that adept meditators have been able to achieve control over various autonomic physiological functions [see Pelletier and Peper (1977a), Pelletier and Garfield (1977), Akishige 1974a), Wallace (1971), Kasamatsu and Hirai (1966), Anand et al. (1961a), Wenger and Bagchi (1961), and Bagchi and Wenger (1957)]. Orme-Johnson and Farrow (1977) and Hjelle (1974) viewed TM as a method of increasing inner control. Hirai et al. (1977) compared twelve Zen priests and disciples with sixteen students with no meditation experience in their ability to control skin potential response using biofeedback. They found that, although the Zen group had greater frequency of potential response, both groups were equally able to produce more spontaneous skin responses during biofeedback periods than during control periods, suggesting that biofeedback training is independent of Zen training.
Earlier, after claims that certain yogis were able to learn cardiac control, and after some even demonstrated a capacity for stopping the heart, Wenger et al. (1961) conducted an extensive investigation with elaborate equipment. Since none of the yogis they studied could stop their heart, the investigators concluded that the disappearance of the heart activity signal was probably an artifact, since the heart impulse is sometimes obscured by electrical signals from contracting muscles of the thorax [see Wallace and Benson (1972)]. Wallace (1971) stated that TM can change a variety of autonomic body functions, including brain waves, rate of respiration, blood pressure, oxygen consumption, spontaneous galvanic skin response, blood pH, and lactate, and these changes persist after meditation has ended, which may account for reports of an afterglow effect in the waking state after meditation. Wenger and Bagchi (1961) observed yogis who could perspire from the forehead on command, regurgitate at will, defecate at will, and draw water into the bladder using a tube. They concluded, however, that such direct voluntary control was achieved by employing intervening voluntary mechanisms. Bagchi and Wenger (1957) believed that the superb respiratory control that yogis exhibited was due to the importance of breathing exercises used in almost all forms of meditation.