An important part of the practice of yoga nidra is the rotation of awareness through different parts of the physical body. It is specifically designed to withdraw perception from the outside world, induce introspection and also deep relaxation of the mind and body.
According to yogic scriptures there are seventy-six physical centres in the body. Technically, they are called angasthana (limb or organ locations) and adhara (physical bases or centres). The latter are mentioned in the Yoga Chudamani Upanisliad. These centres include both the outer limbs such as the hands, arms, legs, etc. as well as the internal limbs such as the heart, lungs, stomach etc. Most of these centres will be listed when we describe the full practice of yoga nidra.
Yoga nidra induces a state of pratyahara (sense withdrawal) in which perceptions of the outside world in the form of taste, smell, hearing, seeing and touch sensations are stopped. This enables awareness to be directed inwards. The sense impressions are not cut off immediately, however, since for most people this is completely impossible. Instead the practice of yoga nidra is so designed that one’s awareness is slowly weaned away from the outside world. In the practice of rotating one’s awareness through the different parts of the body the eyes are closed. This prevents sight perception. If one is aware of the different parts of the body, then one will also cease to smell and to taste. Three of the five sense organs will be closed. Only sense impressions from the instructor’s voice and the mental touch sensations of the physical limbs will be perceived. The field is narrowed. The mind is rendered one-pointed.
Another important thing to remember is that it is difficult to rotate awareness through the different physical centres and be immersed in the normal chattering thoughts of the mind. Either the internal dialogue of thoughts continues and you forget to rotate your awareness through the centres, or you consciously rotate your awareness and cease to be absorbed in bubbling thoughts. You either do one or the other. If you are practising yoga nidra correctly then your chattering thoughts will stop.
In later stages of yoga nidra, rotation of awareness through the physical centres is discarded. If you have been aware throughout the practice of yoga nidra then you will cease to be aware of the physical body, for the sense of touch will be cut off. The only remaining link with the outside world is the sound of the instructor’s voice. This too can be easily cut if the teacher ceases to speak. If he chooses the right time then you will be suspended in a state of pratyahara. You will be ready to begin dharana as the preliminary for dhyana.
The purpose of rotating awareness through the different parts of the body is to enable the body to be transcended. The mind becomes one-pointed and very relaxed. This induces simultaneous relaxation of the entire physical body. Consequently the whole body-mind is rested. Tensions are soothed away.