What is the evolutionary function of dreams?

I always thought it was to order your thoughts, but recently I have started thinking that they are to be analysed like a window into the soul. I think it has something to do with how some people don't remember their dreams and others remember them vividly.

Anon's thought?

The purpose of dreams are to release stored neuron energy in preparation for the next day.  Traditionally, this has lead people in to believing in gods, angels, faries, and werewolves.