The remembered story of the dream is the manifest content. The true meaning of the dream underlies the actual meaning. There is some research that REM sleep helps facility memories. They reflect the on-going, daily activities. So dreams provide the brain with periodic stimulation.
Dreams are just the brain's way of making sense of random neural activity.
The brain transmits a pattern of signals to the cerebral cortex and the cortex attempts to integrate the signals into a dream plot, but has difficulty because the information is random. Dreams are just bits of the process of the mental clean-up that is taking place. For the next week, you are to keep a dream journal. When you wake up, write down what your dream was about. The Sleepnet site lists a number of different sleep problems.