I have studied about 120 articles published in professional journals dealing with the medical or psychological aspects of yoga. In addition I am aware of some 200 other papers in existence. Of these, the majority are clinical and experimental papers, although some theoretical papers and essays have also been published. Articles are mainly concerned with physiology and neurophysiology. Others are concerned with psychiatry and internal medicine. Meditation has been extensively investigated, with less work being concerned with asanas and pranayama. Of the 120 papers in my collection almost 45% were published after 1975. This is a clear indication that the professional interest of medical men and psychologists in yoga has been steadily increasing during recent years.
Physiological research on yoga helps to generate better scientific understanding and can also create theoretical facilities for the correct use of yoga in clinical medicine and prevention. The positive experimental evidence backed by the medical and psychological sciences points to the efficacy of yoga practices, even for those who are dubious. One example has been the intensive study of the physiological effects of meditation.
Various researchers have found conspicuous electroencephalographic changes, decreased respiration rate, decreased metabolism, etc. A very important question has to be asked from a theoretical and practical point of view: How does regularly performed meditation influence the body and the brain outside of the practice? M. West, for instance, states in his review article that "there is some slight evidence which suggests that regular meditation practice produces a decrease in arousal and arousability outside meditation itself." There are also indications that meditation is associated with a decrease in anxiety and an increase in the subjective feeling of relaxation. Psychiatrists and psychologists have clinically investigated meditation and other yogic practices, and found them competent, especially for states of increased anxiety.
The psychotherapeutic effects of yoga are interpreted mostly in psychological terms. Mauphin, for instance, explains them psychoanalytically by 'adaptive regression', i.e. a certain return to childhood emotional experiences. Tart compared relaxed meditation (or the technique of antar mouna, inner silence), during which various thoughts appear, with the technique of desensitisation in which an originally fearful object loses its fearfulness gradually when it is imagined in the state of relaxation. The psychotherapeutic effects of asanas and pranayama could be interpreted similarly, because these should also be performed in a relaxed way. Many psychotherapists believe that the manipulation of the body or breath can release unconscious material or memories.
Yoga has also indirectly influenced psychotherapy. The founder of autogenic training, Prof. Schultz, studied yoga and it was one of the sources from which he derived his well known technique. The influence of yoga in sophrology, practised chiefly in France and Spain, is even stronger.
Drug addiction, being an increasing problem world-wide, is also related to psychiatry, and hence research into the effects of meditation. Decrease in the use of drugs and alcohol after regular meditation is described by various authors. However, the fact is disregarded that fifteen days of abstinence from medically un-prescribed drugs is required before starting the training of meditation. For those who have a heavy drug dependency, this is difficult, whereas a man who never abuses drugs can easily accomplish this. Therefore it is only possible at present to consider as proved the preventive effect of meditation on alcohol and drug dependency.
The prevention of stress in society today is also an important topic for research. Patricia Carrington and co-workers reported the use of two meditative techniques derived from yoga in a study on stress in employees of a New York telephone company. An adaptation of mantra yoga was utilised. From the yogic viewpoint this is unfortunate because the practice is deprived of the specific effect of the mantra. However, on the other hand, the fact that even these adaptations work can be considered as evidence of the effectiveness of mantra yoga. The other technique was the progressive relaxation of Jacobson.
They found that the subjective symptoms of stress decreased in both the meditating group and the relaxation group. However, the decrease in the stress symptoms of meditators was greater. The paper points out the importance of the prevention of stress in terms of stress related diseases among the working population. Naturally such prevention is advantageous for employees, employers and the state, because by removing excessive stress and encouraging better health, the productivity of work can increase. Therefore, if it is correctly performed, mantra yoga seems very safe. The only complication these researchers found was attributed to over-meditation at the beginning of practice.
Yogic and yoga-derived practices have been used successfully, according to Japanese author Goyeche, in many psychosomatic conditions. Several first-rate research papers on the use of meditation and relaxation techniques on patients with high blood pressure have also been published. Prof. Datey from India utilised shavasana, Patel combined yogic relaxation with biofeedback, and Stone and De Leo used simple Buddhist meditation techniques. It has been proved that yogic practices are a valuable adjunct in the treatment of patients with high blood pressure.
It is known that high blood pressure increases the risk of various diseases, especially of the heart, brain and blood vessels. Yoga practice is very valuable in their prevention also, and this we know because there is indirect evidence from various studies. For example, the cholesterol level in the blood decreases in people with hypercholesterolemia after regular practice of meditation. Patel also found a decrease in smoking after yogic relaxation and biofeedback, thereby lessening the risk of arterial disease.
Further, I refer to M.K. Tandon's paper on the rehabilitation of patients with chronic, severe airways obstruction. He found that yogic practices were more effective than the usual rehabilitation procedures. Hornsberger and co-workers report that after regular practice of transcendental meditation, their patients suffering from bronchial asthma improved. Ainslie Meares from Australia likewise used an adapted yogic meditation (not mantra yoga) for cancer patients.
Dr. Meares' experience with 73 advanced cancer patients who attended at least 20 sessions of intensive meditation indicates that nearly all the patients had a significant reduction of anxiety and depression together with much less discomfort and pain. Overall, the results show that patients with advanced cancer have a 10% chance of regression of growth, a 50% chance of greatly improved quality of life, and, for those who die, a 90% chance of death with dignity.
Yoga can be practised for various aims. Its qualified clinical and preventive use is enticing. It is inexpensive and relatively very safe. Active collaboration with the patient is emphasised, and it can be adapted to suit the mentality of different people. Yoga can also be incorporated into various systems of treatment and prevention. It has already enriched western medicine and can continue to play a greater role in the future.