"In your sleep, when your conscious mind becomes less active, your subconscious mind becomes more dynamic and expands out of the body.
Your conscious mind is your conscious-self or conscious-awareness. Your subconscious mind is your subconscious-self or subconscious-awareness.
So, when your conscious-self is less active, your subconscious-self expands itself out of the body to merge into the ether; therefore experiences flashes of images of places, events, and people.
How To Step Into The State Of Flow And Speed Up Your Manifestations Beyond the Pressure Of Time
Now, in your waking state, when your conscious-self happens to be drawn by the subconscious mind into those places, events, and connections with people, your brain experiences a flashback as if what your subconscious-self saw in the dream state was actually a memory now activated called Deja vu.
If you can vividly dream your desire into sleep each night for ninety days straight, your subconscious-self will treat the dream of the desire as an actual event and the manifestation of the event in the physical world will feel like a Deja-vu." - Alain Dagba