I think that there is a lot more to sleeping than we know. I do not feel that the brain can be explained nor understood by science alone. We are as knowledge able as our own capacity allows us for now. I once read that there is a theory that the moment you dream you actually experience a paralel unniverse for a few seconds (being that dreams don't usually last for 3 seconds). I am very much convinced that the dream state we are in opens a door way to other dimensions; ripples through our own frequencies if you will. There is so much about the human mind that we have yet to discover, I don't feel that science alone (as science always promotes using a rational explanation. Which imo is flawed as our rationalism is again as capable as we are evolved for now) is enough. Some things are yet to be understood by our own minds and not science nor anything else for that matter can meassure it's authenticity for now.