Yoganidra Gitavijnan Yogabhyas

Yoga nidra or "yogic sleep" is a state of consciousness between waking and sleeping, like the "going-to-sleep" stage. It is a state in which the body is completely relaxed, and the practitioner becomes systematically and increasingly aware of the inner world by following a set of (audio) instructions.
This state of consciousness (yoga nidra) is different to meditation in which concentration on a single focus is required. In yoga nidra the practitioner remains in a state of light pratyahara with four of his senses internalised (withdrawn) and only the hearing still connects to the instructions. The yogic goal of both paths, deep relaxation (yoga nidra) and meditation are the same, a state called samadhi.