Random is the key word here. About every 90 minutes the brain stem sends electrical impulses throughout the brain, in no particular order or fashion. It is like looking at a Rorschach test, a random splash of ink on paper. This doesn't mean that dreams are meaningless or should be ignored. They are like a TV show, with scenes, characters and props.
Dreams are egocentric.
They almost always involve you. Dreams incorporate things that have happened to you recently. They can also contain deep wishes and fears. A noise in the environment is often worked in to a dream in some way, giving some credibility to the idea that dreams simply are the brain's response to random impulses. Dreaming is important.