Ok first I wrote this and maybe it is not an any way posible but i wrote it for a paper in physics, we had to write our own theory about any topic and have one other theory and/or experiment to back it up:

Dream theory:

The theory that when you are dreaming, you are not dreaming because you brain uses its sub-conscious power to recreate images, pictures, and/or memories. Instead you brain sends a signal telling your body that it is an a sub-conscious state and allows your body to move, change forms, and identities without affecting you "normal" life and identity. Your body is allowed to do this by traveling through a wormhole to multiple universes. The reason you can't take or bring anything back is because while you are traveling your body is changing identities, not allowing your "normal" identity to be effected. When you travel back to the universe your normal identity is from you mind remembers only fragments of you journeys. For people who are gonna ask if your body travels then why if I watch my friend he doesn't travel. Well that can be explained easy through demonstrating the double split experiment. For people who don't know want that is, it's an experiment where you fire a particle at a piece of paper with two slits when studied the particle goes through one or the other never both. But when not studied the particle will go through both every once in a while showing that the particle was at two different places at once.

The paper isnt finished but anyone like where it is going?