This is a great article on including dreams in novels. Click on the below link. There are also some great passages below.
When considering the relevance of your dream sequence, think about what revelation or clue to a revelation the dreaming character is obtaining. If there are no clues or revelations, it may be that the dream is meant to haunt the character by bringing up a painful, or perhaps guilt-ridden, memory. If none of these factors apply, you may want to rethink whether to include the dream sequence at all. Oftentimes irrelevant dream sequences make their way into drafts of a novel because the authors like how they were written. Make sure you’re not shoehorning a dream sequence into the story just because.