Basically, the human body and its functions are regulated through nervous system consisting of brain, spinal cord and nerves. The nervous system has two distinct parts : one part is under the voluntary control and most of the ordinary functions of the body like walking, doing work manually, etc. fall under the category of voluntary control. Many vital functions of the body like respiration, circulation, digestion, etc. are involuntary. This system which controls vital functions, is known as autonomous nervous system. It consists of two parts, parasympathetic and sympathetic. One which comes into action in emergency is called a sympathetic system. Activation of this part increases adrenaline and corticosteroid hormone secretions leading to increase in heart rate, raising of blood pressure and clumping of platelets increasing the viscocity of blood. The oxygen consumption of the body increases and so does lactic acid formation in the body. Wear and tear of the body are also increased ; in terms of physics , the rate of entrophy increases.

The technique of Shavasana and meditation brings about its beneficial effects by quietening the sympathetic nervous system. This aspect of yoga has, therefore, particularly attracted the attention of medical science. Moreover, medical scientists have made this technique of meditation and shavasana simple and easy for a beginner.

Shavasana has been considered the king of asanas. The purpose of this asana, as the name suggests, is to assume a dead-body posture. Various techniques are there to perform this asana. The one adopted in the program of Dr. Dean Ornish has been evolved by Swami Satchidanandji settled in Virginia, U.S.A. It relies on the theme that for optimum relaxation of muscles of the body prior stretching of muscles is necessary. This is a wonderful concept. Experience has shown that if relaxation is preceded by stretching, it yields optimum results. A very significant point to remember is that while stretching a particular group of muscles it is not as it were the more stretching, the better the relaxation. The stretching must be just enough to create a pleasant sensation. The awareness of an individual doing this exercise must be focussed on the process of stretching and relaxing. The simple observation that the awareness must be brought on to the part of the body being stretched is the cardinal feature of the technique without which the benefit of shavasana is not complete.

Science has established that our awareness is, for most of the time either in the past or in the future. Out of 16 hours of our waking time, it is hardly for an hour and a half or so that we live actually in the present. It is well known that stress is minimum when awareness is in the present. In shavasana, by various stretching and relaxation exercise of the body and thereby keeping the awareness on the process, progressive deep relaxation is achieved. After lying in supine position with legs about one foot apart and the arms lying by the sides, palms facing the ceiling, fingers half bent, the individual closes his eyes and brings his awareness on to the body. All the muscles of the body right from the heal to the head are contracted and relaxed one by one. When in this manner, a complete relaxation of the muscles of the body is achieved, the individual brings his awareness to the natural process of breathing. He now becomes a witness to his own breathing process without any special effort to breathe in a particular manner. It is only the natural process of inhalation and exhalation that is witnessed. This brings about relaxation and the peace of mind. It is precisely at this stage, when the individual’s awareness gets focussed on the natural process of breathing, that the suggestions are given that all the muscles of the body are now relaxed, and hence the coronary arteries which are made up of muscles are also relaxed. This leads to dilatation of the arteries and increase of blood flow to the heart muscles. It improves the functioning of the heart which in turn increases the perfusion of all the cells of the body with the result that the individual feels very energetic and well. After five to ten minutes of shavasana, the participants sit down in a comfortable posture with their eyes closed and their awareness focussed on the process of breathing. This is all there is to the technique of meditation. When the participants are one with their breath, they say ‘Om’ five times, keeping their awareness on the sound ‘Om’ and thus having experienced oneness with that sound, sit quietly with their awareness on the breath for further five minutes. To be thus in tune with the breathe is to be in tune with the life force also.