Yoga nidra means sleep with a trace of awareness. It can relax the whole system, awaken the psychic body, give one experiences of the astral plane. When you practice yoga nidra you are opening the deeper phases of your mind. At this moment, your subconscious and unconscious levels of the mind open, meanwhile the physical body is relaxing.
Yoga nidra is a very simple practice. Before starting, choose a quite room, wear comfortable clothes, lie down in shavasana, close eyes and listen to the instructions . During the process, try not to falling asleep in order to gain more benefits from the practice.
Here, for the beginners, you can use the below recorded instructions. Wish you a fruitful Yoga nidra!
Basic version of Yoga nidra: