Take up the classic dream of finding a new room or wing of the house you live in (or one that you used to live in). You can either describe a time you had this dream, if you have this dream (supposedly this is a dream archetype, like the unprepared anxiety dream) or use your writing to dream awake, or dream on behalf of a character or figure in the world of your writing.
Write a description of the room and what you found there. Continue your description through waking up. Is it a relief or disappointment to learn the room was only dreamt? What does this tell you or your character about what is missing?