Dreams can be very entertaining. You’re caught up in an experience that can feel very real. It can make perfect sense while you’re immersed in it.
It won’t make for a good story, though, because dreams as stories rarely make sense once you wake up. Sure, they have meaning that can make sense. But the story of your dream doesn’t hold up once you wake. Essentially, when we dream, our mind is communicating with itself. You know what you mean, but that doesn’t mean you can put it to page as it is and have others follow along, too.
Daydreams, too, can make for some intense self-entertainment. But, again, they usually make poor stories for the same reasons.
Stories involve communicating with other people, particularly your readers or your listeners or your viewers, depending on your medium. These people do NOT share your brain, no matter how much you may think they should. They do, in fact, have brains of their own. Your dreams don’t fit inside their brains, because their brains will make different assumptions than your brain does. The holes that your brain automatically fills will leak like a sieve in their brains.
Yet both dreams and daydreams can light a spark that sets a story on fire in your mind. They can be the match that ignites the roiling cauldron of gasoline brewing in your brain.
When that happens, it’s important to leave the dream as a spark. Treat that spark like an idea that needs to be developed into a story, just like any other idea, no matter how whole it seems to be. In other words, you need to plug the holes by communicating with your audience, by filling them with story bits that will make sense, by telling a whole story.