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Research on the processes and effects of meditation is a growing subfield of neurological research.[1][2][3][4][5][6] Modern scientific techniques and instruments, such as fMRI and EEG, have been used to see what happens in the body of people when they meditate, and how their bodies and brain change after meditating regularly.[2][7][8][9][10] Since the 1950s hundreds of studies on meditation have been conducted, though many of the early studies were flawed and thus yielded unreliable results.[11][12] More recent reviews have pointed out many of these flaws with the hope of guiding current research into a more fruitful path.[13] More reports assessed that further research needs to be directed towards the theoretical grounding and definition of meditation.[11][14] Meditation within Western psychology The relaxation response Dr. Herbert Benson, founder of the Mind-Body Medical Institute, which is affiliated with Harvard University and several Boston hospitals, reports that meditation induces a host of biochemical and physical changes in the body collectively referred to as the "relaxation response".[15] The relaxation response includes changes in metabolism, heart rate, respiration, blood pressure and brain chemistry. Benson and his team have also done clinical studies at Buddhist monasteries in the Himalayan Mountains.[16] Benson wrote The Relaxation Response to document the benefits of meditation, which in 1975 were not yet widely known.[17] Calming effects of meditation According to a March 2006 article in Psychological Bulletin, EEG activity begins to slow as a result of the practice of meditation.[18] The human nervous system is composed of a parasympathetic system, which works to regulate heart rate, breathing and other involuntary motor functions, and a sympathetic system, which arouses the body, preparing it for vigorous activity. The National Institutes of Health (NIH) has written, "It is thought that some types of meditation might work by reducing activity in the sympathetic nervous system and increasing activity in the parasympathetic nervous system," or equivalently, that meditation produces a reduction in arousal and increase in relaxation. Western therapeutic use and MBSR See also: Mindfulness (psychology) and Mindfulness-based stress reduction Meditation has entered the mainstream of health care as a method of stress and pain reduction. As a method of stress reduction, meditation has been used in hospitals in cases of chronic or terminal illness to reduce complications associated with increased stress that include depressed immune systems. There is growing agreement in the medical community that mental factors such as stress significantly contribute to a lack of physical health, and there is a growing movement in mainstream science to fund research in this area. There are now several mainstream health care programs which aid those, both sick and healthy, in promoting their inner well-being, especially mindfulness-based programs such as Mindfulness-Based Stress Reduction (MBSR). A 2003 meta-analysis found that MBSR, which involves continuous awareness of consciousness, without seeking to censor thoughts, concluded that the form of meditation may be broadly useful for individuals attempting to cope with clinical and nonclinical problems. Diagnoses for which MBSR was found to be helpful included chronic pain, fibromyalgia, cancer patients and coronary artery disease. Improvements were noted for both physical and mental health measures.[19] Flow Mindfulness meditation, anapanasati, and related techniques, are intended to train attention for the sake of provoking insight. A wider, more flexible attention span makes it easier to be aware of a situation, easier to be objective in emotionally or morally difficult situations, and easier to achieve a state of responsive, creative awareness or "flow".[20] Research from Harvard medical school also shows that during meditation, physiological signals show that there is a decrease in respiration and increase in heart rate and blood oxygen saturation levels.[21] Research by style of meditation Insight meditation Main article: Insight meditation#Scientific studies A study done by Yale, Harvard, Massachusetts General Hospital have shown that meditation increases gray matter in specific regions of the brain and may slow the deterioration of the brain as a part of the natural aging process. The experiment included 20 individuals with intensive Buddhist "insight meditation" training and 15 who did not meditate. The brain scan revealed that those who meditated have an increased thickness of gray matter in parts of the brain that are responsible for attention and processing sensory input. Some of the participants meditated for 40 minutes a day while others had been doing it for years. The results showed that the change in brain thickness depended upon the amount of time spent in meditation. The increase in thickness ranged between .004 and .008 inches (0.1016mm – 0.2032mm).[22][23] Kundalini yoga meditation Main article: Kundalini yoga#Medical research There have been some preliminary studies done on some of the many types of meditation found within the branch of Yoga known as Kundalini. One study showed the cooling of meditators hands as they practiced Sahaja Yoga meditation and another study showed some relaxation while meditators paid attention to their breathing. A study comparing practitioners of Sahaja Yoga meditation with a group of non meditators doing a simple relaxation exercise, measured a drop in skin temperature in the meditators compared to a rise in skin temperature in the non meditators as they relaxed. The researchers noted that all other meditation studies that have observed skin temperature have recorded increases and none have recorded a decrease in skin temperature. This suggests that Sahaja Yoga meditation, being a mental silence approach, may differ both experientially and physiologically from simple relaxation.[24] Integrative body-mind training A study involving the participation of a group of college students, who were asked to use a meditation technique called integrative body-mind training (IBMT involves body relaxation, mental imagery, and mindfulness training), concluded that "meditating may improve the integrity and efficiency of certain connections in the brain" through an increase in their number and robustness[25] Brain scans showed strong white matter changes in the anterior cingulate cortex.[26] Zazen Dr. James Austin, a neurophysiologist at the University of Colorado, reported that meditation in Zen "rewires the circuitry" of the brain in his book Zen and the Brain (Austin, 1999). This has been confirmed using functional MRI imaging, a brain scanning technique that measures blood flow in the brain.[citation needed] Theoria Fifteen Carmelite nuns came from the monastery to the laboratory to enter a fMRI machine whilst meditating, allowing scientists there to scan their brains using fMRI while they were in a state known as Unio Mystica (and also Theoria).[27] The results showed that far-flung parts of the brain were recruited in the sustaining of this mystical union with God.[27] The documentary film Mystical Brain by Isabelle Raynauld examined this study.[28] Non-referential compassion meditation See also: Metta Electroencephalograph (EEG) recordings of skilled meditators showed a significant rise in gamma wave activity during meditation, somewhere in the 80 to 120 Hz range. There was also a rise in the range of 25 to 42 Hz. These meditators had 10 to 40 years of training in compassion meditation training and were engaging in non-referential compassion meditation during the study. The experienced meditators also showed increased gamma activity while at rest and not meditating.[29] Several controls who hadn't practiced meditation before were compared to the highly trained monks and showed significantly less rise in gamma activity during meditation.[29] Transcendental Meditation Main article: Transcendental Meditation It is presently not possible to say whether meditation has any effect on health, as the research to date has been of poor quality,[30][31][32] including a high risk for bias due to the connection of researchers to the TM organization and the selection of subjects with a favorable opinion of TM.[33][34][35] Independent systematic reviews have not found health benefits for TM exceeding those of relaxation and health education.[30][36][37] A 2013 statement from the American Heart Association described the evidence supporting TM as a treatment for hypertension as Level IIB, meaning that TM "may be considered in clinical practice" but that its effectiveness is "unknown/unclear/uncertain or not well-established". The section on meditation finished by stating: "Because of many negative studies or mixed results and a paucity of available trials... other meditation techniques are not recommended in clinical practice to lower BP at this time."[38] There has been ongoing research into Transcendental Meditation since the first studies were conducted at UCLA and Harvard University and published in Science and the American Journal of Physiology in 1970 and 1971.[39] By 2004 the US government had given more than $20 million to Maharishi University of Management to study the effect of meditation on health.[40] Research by effects of meditation Brain activity during meditation The medial prefrontal and posterior cingulate cortices have been found to be relatively deactivated during meditation (experienced meditators across all meditation types). In addition experienced meditators were found to have stronger coupling between the posterior cingulate, dorsal anterior cingulate, and dorsolateral prefrontal cortices both when meditating and when not meditating.[41] Brain waves during meditation During meditation there is a modest increase in slow alpha or theta wave EEG activity.[29][42] Meditation and perception Studies have shown that meditation has both short-term and long-term effects on various perceptual faculties. In 1984, Brown et al. conducted a study that measured the absolute threshold of perception for light stimulus duration in practitioners and non-practitioners of mindfulness meditation. The results showed that meditators have a significantly lower detection threshold for light stimuli of short duration.[43] In 2000, Tloczynski et al. studied the perception of visual illusions (the Müller-Lyer Illusion and the Poggendorff Illusion) by zen masters, novice meditators, and non-meditators. There were no statistically significant effects found for the Müller-Lyer illusion, however, there were for the Poggendorff. The zen masters experienced a statistically significant reduction in initial illusion (measured as error in millimeters) and a lower decrement in illusion for subsequent trials.[44] The theory of mechanism behind the changes in perception that accompany mindfulness meditation is described thus by Tloczynski: “A person who meditates consequently perceives objects more as directly experienced stimuli and less as concepts… With the removal or minimization of cognitive stimuli and generally increasing awareness, meditation can therefore influence both the quality (accuracy) and quantity (detection) of perception.”[44] Brown also points to this as a possible explanation of the phenomenon: “[the higher rate of detection of single light flashes] involves quieting some of the higher mental processes which normally obstruct the perception of subtle events.” In other words, the practice may temporarily or permanently alter some of the top-down processing involved in filtering subtle events usually deemed noise by the perceptual filters. Sleep need Kaul et al. found that sleep duration in long-term experienced meditators was lower than in non-meditators and general population norms, with no apparent decrements in vigilance.[45] Elevation of positive emotions and outcomes Schoormans and Nyklicek (2011)[46] compared well-being measures for two groups that had each practiced a different meditation—mindfulness meditation (MM) or transcendental meditation (TM). Authors believed that MM would increase mindfulness and psychological well-being more than would the TM. In fact, MM and TM practitioners had very similar mindfulness and well-being outcomes. The only predictor of higher mindfulness and reduced stress was the number of days meditated per week, with more days associated with higher mindfulness and reduced stress. Barbara Fredrickson assessed a loving-kindness meditation in 2008 and found an increase in positive emotions and life satisfaction when controlling for personal resources.[47] Potential adverse effects of meditating The following is an official statement from the US government-run National Center for Complementary and Alternative Medicine: Meditation is considered to be safe for healthy people. There have been rare reports that meditation could cause or worsen symptoms in people who have certain psychiatric problems, but this question has not been fully researched. People with physical limitations may not be able to participate in certain meditative practices involving physical movement. Individuals with existing mental or physical health conditions should speak with their health care providers prior to starting a meditative practice and make their meditation instructor aware of their condition.[48] Adverse effects have been reported,[49] and may, in some cases, be the result of "improper use of meditation".[50] The NIH advises prospective meditators to "ask about the training and experience of the meditation instructor... [they] are considering."[48] As with any practice, meditation may also be used to avoid facing ongoing problems or emerging crises in the meditator's life. In such situations, it may instead be helpful to apply mindful attitudes acquired in meditation while actively engaging with current problems.[51] According to the NIH, meditation should not be used as a replacement for conventional health care or as a reason to postpone seeing a doctor.[48] Kundalini syndrome is a claimed adverse effect from practicing Kundalini Yoga (or other related spiritual practices).[citation needed] Research methodology A comparison of the effect of various meditation techniques on systolic blood pressure.[52]In June, 2007 the United States National Center for Complementary and Alternative Medicine (NCCAM) published an independent, peer-reviewed, meta-analysis of the state of meditation research, conducted by researchers at the University of Alberta Evidence-based Practice Center. The report reviewed 813 studies involving five broad categories of meditation: mantra meditation, mindfulness meditation, yoga, T'ai chi, and Qigong, and included all studies on adults through September 2005, with a particular focus on research pertaining to hypertension, cardiovascular disease, and substance abuse. The report concluded, "Scientific research on meditation practices does not appear to have a common theoretical perspective and is characterized by poor methodological quality. Firm conclusions on the effects of meditation practices in healthcare cannot be drawn based on the available evidence. Future research on meditation practices must be more rigorous in the design and execution of studies and in the analysis and reporting of results." (p. 6) It noted that there is no theoretical explanation of health effects from meditation common to all meditation techniques.[53] A version of this report subsequently published in the Journal of Alternative and Complementary Medicine stated that "Most clinical trials on meditation practices are generally characterized by poor methodological quality with significant threats to validity in every major quality domain assessed". This was the conclusion despite a statistically significant increase in quality of all reviewed meditation research, in general, over time between 1956–2005. Of the 400 clinical studies, 10% were found to be good quality. A call was made for rigorous study of meditation.[13] These authors also noted that this finding is not unique to the area of meditation research and that the quality of reporting is a frequent problem in other areas of complementary and alternative medicine (CAM) research and related therapy research domains. Of more than 3,000 scientific studies that were found in a comprehensive search of 17 relevant databases, only about 4% had randomised controlled trials (RCTs), which are designed to exclude the placebo effect.[11] Reviews of these RCTs consistently find that meditation without a focus on developing "mental silence", an aspect often excluded from techniques used in Western society, does not give better results than simply relaxing, listening to music or taking a short nap. While those who practiced mental silence showed clinically and statistically significant improvements in work related stress, depressed feelings, asthma-control, and quality of life as compared to commonly used stress management programs.[54][unreliable source?] |
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