Very nice howto on how to think about dreams.

I do agree on the part that what you dream is mostly related to what is actually happening in your life.

Since I am an engineer in computer science I see dreams as a processes in which your mind program itself for future events.
Simply your mind must anticipate and prepare for as many possible events as possible to succeed in life.
One of the way of achieving this would be to take all recent events from the memory and mix them all together. This process could be easily hidden from us, but for more accurate results it is better to involve the whole consciousness in the simulation.

If the brain was depending solely on the regular processing in many situations it would be simply a bit too slow.

These recipes can be considered as knee like reactions/reflexes, but for more complex and cognitive scenarios.