Question

With God's help,
Hello Rabbi,
What is your view on how a person distinguishes between being inside a dream and being in reality? Is it through some kind of shifting memory, like a flip-flop, so that through certain psychological influences one could cause him to switch his sensations in a fixed way? Or is it a more intuitive kind of understanding?
I'm asking because we find that certain psychological phenomena can affect a person so that he experiences a dreamlike feeling even though he understands that he is not in a dream — derealization disorder. So there seems to be some deceptive and unclear factor here.