Sutra I. 38 Svapna-nidra-jnanalabanam va

Commentary; Every night we sleep and dream. This is a wonderful opportunity when the will, the intellect, and limited belief systems rest and no longer dominate our experience. Normally when this limitation disappears, our cognitive faculty is given up as well so that the dreams are not integrated, but are relegated to a subconscious level. But if we are able to relax the mind while remaining conscious and aware, but at the same time watch the mind make its apparently random associations then a higher trans sequential knowledge (janam-alabanam) far deeper than the straight plane three dimensional daytime consciousness will come forth allowing us to glean information, instruction, and perform duties from the dream state as an astral body. this in turn will augment and extend our awareness and lucidity in daily life. The lucidity that links both dream and ordinary wakefulness is eventually disclosed as the clear light that knows no sorrow. Yoga nidra is similar where the yogi enters this dream state consciously in order to interact in the fourth and greater dimensions (turiya). See I.10 for the "vrtti of sleep (nidra).

There is a well known hatha yoga practice called yoganidra, which is deeply relaxing, yet one does not lose consciousness. It is designed in order to experience a state deeper than the ordinary superficial aspects of the physical body and ordinary mentation by focusing on the marma points and then nadis (energy channels). Here one utilizes asana, pranayama, pratyhara, and dharana (as inner visualization) all at once to access the yantra or sacred mandala where the physical body, energy body, mental body, and wisdom body are potentially capable of energizing and invoking as a portal. Here deep rest and astral travel are both made possible. Knowledge of the future, the past, and distant places are experienced directly. The mind and nervous system abide in deep rest and harmony according to how much attention one gives to the practice.