Dreams are the expressions of your subconcoius mind, very often if we are worried about things we will have very vivid dreams losely connected to that worry, and wake up feeling much better about the thing we were worring about (hence the phrase 'sleep on it'). The reason we dream is argued continously, and deprived of dreams we quickly become psycotic, depressed and violent. I think dreams are the only way we have to deal with the chaos of the crazy world we live in.
Because dreams are the subconcious mind, our concoius mind only interprets them in unusual, unconnecting ways, much like reflex images flashing away in our minds which we have no control of, and our brains learn very early on not to remember them as the would confuse our waking minds. occasionally we repeat the same dreams (normally because of a repeating problem in our lives) and these dreams become easier to remember.
The part im facinated about is the instant where we actually fall asleep and detach our minds from our bodies and give way to the subconcoius mind. During this time our bodies are paralysed and the only two things that we control is our breathing and eye movement (dreams a catagorised by R.E.M. sleep - Rapid Eye Movement). At the point where the concoius mind switched off there can often be a spark where it doesnt quite switch off cleanly and our bodies jerk, often as if recieving an electrical shock. and we all know what that feels like.