Dreaming is a 'file' sorting process a bit like what Defrag does for a hard drive; you're sleeping so that your data areas can be sorted, tidied, assessed and acted upon; this why your dreams can be surreal but also communicative; your unconscious is trying to tell you something by use of analogy and symbol as these are the tools of mind that it's using to tidy up your thought processes. IMO.
I don't think that dreams have any real meaning, like these books on dreams have us believe. i'm always dreaming about aeroplane crashes, that are either into a river or in a field next to it, but it doesn't mean i've predicted a crash it's probbly due to the fact that i live next to a river near a airport under a flight path, i see the river everyday and hear the planes whilst i'm asleep. You may see something during the time you're awake e.g a t.v programe that's relevant to you or has an effect on you or perhaps it could be a perso /object, then a few days later you have a dream containing the things you've seen during that period when you were awake. i agree with xyzzy your brain is like a file and it needs to be put into order.
Not being condescending but;
Life is a theory daviduk, so is God, death, time, extraterrestrial life, evolution, and ghosts in machines; but we got to start somewhere or we'd still have belief in magic, superstition and the Earth as galactic central point, [who says we don't?] :-)