Here is some interesting information on Yoga Nidra

In Yoga Nidra, you leave the Waking state, go through the Dreaming state, and into the Deep Sleep state, yet remain fully awake.

Yoga Nidra, may be translated in English as "yogic sleep" or "sleep of the yogis". There are many traditions of Yoga Nidra that show up in Indian religions. These aspects may include disciplines and traditions of dream, sleep, and yoga.

Yoga Nidra is engaged to help a person grow spiritually, emotionally, mentally and physically, before seeking sublime levels and aspects of consciousness and awareness through meditation and trance.

General traditions of Yoga Nidra have a version that has become synonymous with yogic relaxation and guided visualization techniques.

In some traditions, Yoga Nidra is employed to purify the unconscious mind through use of certain vows and commitments.

A half an hour of Yoga Nidra may yield the benefit of up to three hours of standard sleep.

Yoga Nidra is deeply relaxing, and is used by the yogis to deal with samskaras (the deep impressions that drive karma) in their latent form.

Yoga Nidra provides an incredible calmness, quietness and clarity. Yoga Nidra is one of the deepest of all meditations, leading awareness through many levels of mental process to a state of supreme stillness and insight.

As a state of conscious deep sleep, Yoga Nidra is a universal principle, and is not the exclusive domain of any specific tradition.

Yoga Nidra is best engaged as a guided, facilitated practice, that is, with an experienced yoga teacher who verbally delivers the instructions.

Important Yoga Nidra entities:

Vishnu: The Sleeping Lord

In a few texts like the Devi Mahatmya and the Bhagavata Purana, Vishnu reclines on the Naga Shesha while practicing Yoga Nidra. The world is the dream of Vishnu.

Swami Satyananda

He particularly began popularizing the practice about 40 years ago. He drew a connection to the ancient tantric practice called nyasa, whereby mantras are mentally placed within specific body parts, while meditating on each part.

Swami Rama

His teachings on Yoga Nidra continue to be taught through his Himalaya Institute and several of his non-affiliated students.

Hypno-Yoga Nidra

The Hypno-Yoga Nidra practice that Brian Stracner developed is a multi-faceted art, which emphasizes:

• Stimulation of both hemispheres of the brain
• Awareness of the physical body and breath
• Systematic desensitization to neutralize and resolve negative sensation, stress, emotion, belief, image, and memory
• An experience of joy and well-being
• The embodiment of equanimity amidst the ever changing situations in life
• Metaphors for inner self growth
• Learn how to smile from deep within