This might be a classical question and it might be interpreted as an argument against vedanta but I'll put my thoughts here and invite you to discuss:
My awareness is limited to my personal body. I sleep and I wake up and I find a permanence of experience. However if I am really consciousness, why am I not experiencing consciousness of everything in the universe simultaneously? Why is this consciousness locked on to my body? Logically it makes sense for my consciousness to permeate the entire universe much akin to that of Brahman.
Vedanta says that the knower and the known are different. This is how we arrive at the conclusion that 'sakshi' or the witness consciousness is a different entity from that what is observed implying that this mind and its witness are different but is this claim backed by any logic? Why is it impossible for the mind which forms all kinds of sensations to not have a sensation of 'itself'. The way I see it, the mind has all power to conjure up an image of itself. And that is where the matter would end. When one is under a deep meditation or anesthesia, one can forgo this sense of self and see experience for what it is, detached from his own body. Then if you up the dose or the depth of meditation, even those experiences vanish. Thus ultimately, I arrive at the conclusion that the consciousness we associate with ourselves is vastly different from the universal consciousness.