well from a scientific perspective a dream is your brain trying to figure out those daily or reoccuring problems u face
its like natures was of brainstorming no matter how rediculous the dream some how we learn from them
basicly during sleep your logic shuts down and the active brain takes over.
things that are on your mind are in essence acted out.
have u ever noticed people saying "let me sleep on it"
usually you wake up feeling good and the problems u have dont seem so bad, or an answer is not far.
i wish i had the energy to expand on this but its late and i must be off to school in the morning