Yoga Nidra, OM Consciousness  and  Mandukya Upanishad

The purpose of deep Om meditation is to transform the deep impressions or samskaras.  In the formless state of the conscious, there is only awareness. Yogic sleep or sleep of awareness is known as Yoga Nidra. Mandukya Upanishad is talking about the awareness in deep sleep.   It is an ancient yoga practice, in west it is known as full-body relaxation and a deep meditation.  It is a very old somatic science. It is practiced by all almost all India Originated religions. It is a very common practice for the Hindu Yogi and the Buddhist monks for centuries.
It is not exactly the Out-of-the-body experiences (OBEs). It is also different from Lucid Dreaming. But you can use Lucid Dreaming techniques and the Out-of-the-body experiences for realizing the higher truths. Some people uses Alarm clocks to experice the dreaming state. But Alarm clocks are often disturbing, so stop using them if you want to retain dreams. Yoga exercises like kundalini yoga are the best thing to experiennce the awakening state of relaxation.
Vitamin B-6, Niacin or Nicotine patches and Zinc promotes Serotonin production and more Melatonin is metabolized. Melatonin increases non-REM sleep and makes it easier for you to fall asleep. But it has also an interesting rebound effect that gives more frequent and vivid dreams. The vividness might even give you a glimpses of reality.
You can keep note book of your dreams.
If you are aware that you are dreaming can you develop full conscious control over all the states of consciousness. But please do not disturb your regular sleep. Prolonged sleep deprivation causes severe mental disturbance, attention deficit, withdrawing, visual complaints, hallucinations and time distortion. Always take expert's advice. The beauty is; there is no dearth of expert in this world.
So, let us start.
First we will discuss more about the reality, the absolute truth. Then we will discuss more, how these realities can be experienced in the dream state and in the awaking state. Mandukya Upanishad is very close to yoga nidra. We can say yoga nidra is the starting point of Mandukya Upanishad. Deep sleep awareness is the next step of yoga nidra.

Mandukya Upanishad Verses

The Nature of Self the Absolute:

1.       The syllable Om, Ohm or AUM** is everything. Now, is the explanation of OM: The past, the present and the future are OM, and beyond these three is also OM.          

2.       Brahman is indeed all this. This self in us is also Brahman. And this self has four levels of consciousness.

Four Levels of Consciousness:

3.       Vaisvanara is the first stage. Wakeful, outwardly conscious, With seven limbs and nineteen mouths, he is the enjoyer of the gross objects.

4.       Taijasa is the second stage. Dreaming, inwardly conscious, With seven limbs and nineteen mouths, he is the enjoyer of the subtle objects.

5.       In deep sleep, seeking no desires, dreaming no dreams, unified into the mass of higher consciousness, full of bliss, enjoying bliss only, face turned towards Chetasa, is Pragna the third stage.

6.       This is the Master of All, the Omniscient, the Inmost Dweller and source of Creation and destruction of all beings.  

7.       Conscious neither internally nor externally, Nor either ways, neither ordinary consciousness, Nor the greater and the deeper consciousness, Invisible, otherworldly, incomprehensible, Without qualities, beyond all thoughts, Indescribable, the unified soul in essence, Peaceful, auspicious, without duality, Is the fourth stage, that self, that is to be known.

Interpretations of the letters of Om (AUM)

8.       The same Atman is OM among the syllables, each letter in the word AUM is a state. They are the letter A, the letter U and the letter M.

9.       The wakeful Vaishwanara is the first letter "A", being the first letter and all pervasive. He who knows thus realizes all his desires and becomes foremost too.

10.   The dreaming Taizasa is the second letter "U", being superior and situated in the middle. He who knows thus attains knowledge and children equally and none in his family would be ignorant of Brahman.

11.   In the world of deep sleep, Pragna, is the third letter "M", being the limit and the end of all diversity. He who knows thus is free from all diversity and becomes one with the Self.

12.   The fourth state is without parts and entanglements, not bound to this world, It is auspicious and non-dual. Thus the form of AUM is verily the Self itself. He who knows thus enters into his own Self by himself.

Silence after "A-U-M" is the Real Self:

The fourth characteristic is the silence of Om. It is not realized through the senses or by the mind. With the cessation of all phenomena,  this soundless aspect becomes known. It is a state of nondual  reality—one without a second. This fourth state, Turiya, is the real Self or true Self. One with direct experience of this expands to Universal Consciousness.