From a biological perspective, your dreams are part of the process of moving short term memories from the hippocampus to the neocortex. This will involve perceiving symbolic representations of your experiences, feelings, memories, predictions, etc. As far as being "meaningful," that's relative to the implications you're interested in. If you're looking for meaning, look for the common psychological underpinnings of certain symbols (e.g. teeth falling out, not wearing pants, etc.) and see what that might expose about the things your brain is processing. Just remember that specific archetypes are often offered by people based on tradition and superstition; Make sure you're looking at reliable sources, especially considering that your brain is going to process a lot more than people have worked out, and not every archetype is likely to carry information you find meaningful.