[Recent medical research on yoga and states of concentration].

Traditional oriental thinking attracts the growing scientific interest of occidental practitioners. Dr. Pierre Etévenon, head of the Department of Neuro-Psycho-Pharmacology at the French Institute for Health and Medical Research (INSERM), held several conversations and scientific exchanges with the author, and kindly provided copies of some of his works. They are at the basis of the present paper. M. A. Descamps (Paris) found that asanas--yoga postures-- are generators of dynamic action when there is an extension of the spinal column, whilst they lead to quiet states when there is a flexion of it. Claeys and Gones (Belgium) proved that overall global relaxation, as well as differential relaxation were far more effective and deep when obtained by yogis than those attempted by University students majoring in Physical Education. Lonsdorfer and Nussbaum (France) studied several parameters concerning hatha-yoga and concluded that it provides a regular functioning of the main bodily functions fostering thus a psycho-physical balance. Wallace and Benson (U.S.A.) proved that transcendental meditation increases aerobic metabolism, counteracting anaerobic metabolism which is related to mental distress. Etévenon (Paris) investigated neurophysiological effects of yoga in connection to ancient Indian concepts (Upanishads) on sleeping, meditation and degree of consciousness. Dr. Etévenon has studied the phylogenetic evolution of waking-sleeping cycles, focusing on phylogenetic and ontongenetic appearances of REM cycles (activated sleep). A correlation has been made with EEG studies during states of concentration (yoga, transcendental meditation, Zen). These states have been found to be specific brain activities, and different from deep sleep, in spite of certain similarities in the EEG. Several hypothesis are set forth to explain brain activities underlying sites of concentration. The possibilities of developing a conscious mastering of dreams are also under research, and special attention is paid to the works of Saint Denys (1867), and hindu tradition. This paper discusses also the psychological, therapeutic and anthropological implications of recent discoveries in the field.