Due to ignorance of the true self, the waking is experienced as reality.

When one has a dream, what is it? This analysis requires self-elimination, purging of preconceptions.

The dream becomes unreal when waking takes place.

Similarly the waking becomes unreal when wisdom dawns. Hence man and his experience of the world within the waking experience is bound to be unreal. Due to ignorance of the true self, the waking  is experienced as reality.

 The aim of yogic Samadhi is to empty the mind of its contents, but this is successfully achieved by millions of men during the deep sleep state. Yet they never find Truth. That is why something more is needed to acquire non dual wisdom.

Deep sleep is not liberation. It is not Reality. Reality is existence in waking/dream experience, as much as in deep sleep, but only the Gnani can perceive this.

The novices have been told that deep sleep is nearer the Soul or Atman,the innermost self, merely to induce them to begin and carry on the quest which shall pass into and through and out of yoga, until they reach perfect understanding. 

Sleep is gift to people to enable them to contact their divine self nightly.  Deep sleep is simply having no experience. 

The dream- has been given to seeker as an illustration for the purpose of pointing out to him that the waking experience is likewise is mere mirage. One sees a thing in dream as different from him, but yet it as of the same substance – mental - it is not for nothing that dreams exist.

v  How did the sense of reality during the dream arise?

It arises from the Atman, not mind. There is no other illustration but dream which can prove this truth.

If a man in dream knows the waking to be mere mirage, this is a good test that he has reached the higher stage. 

Seeker must think constantly that the waking is an experience till it gets so firm conviction that the proper test of his grasp occurs--when in his dreams he will say to himself too that even his dreams are but mirage.  

He who has realized the ultimate truth or Brahman transcends the duality or mind where he sees no second thing other than consciousness.   Yogi who sees the universe as reality may try to deny it because he thinks thoughtlessness is Brahman.  The yogi sees the universe as a second thing and he wants to banish the universe in Samadhi, because he does not know that in non-duality there is no need to deny the universe. But he has to realize the fact that, universe is not something different from the self, which consciousness. Those who cannot grasp and realize this position, misunderstand it, and wrongly hold it be yogic Samadhi where there is only blankness.  

The presence of the universe is no obstacle to Gnani‘s realization; he does not need yogic Samadhi.  But yogi has imagined Brahman as blankness or thoughtlessness thus he is still in the grip of duality.  Thus Yogis Brahman is but a thought.  Brahman is not a thought but Brahman is prior to any mind or universe.  Thus one has to know what is prior to waking experience.  

The yogi who wrongly thinks there is Brahman to be got ,may attempt to do so, and may think he sees it, but all the time he under the delusion of duality because he bases his- self  on physical body, thinking Brahman to be something different from the soul, which is the true self.

When one becomes aware of the fact all the experiences of the three states and all the thoughts and words are Mind and mind in turn is consciousness then he has transcended thinking faculty.