Henry James or Gertrude Stein or somebody else, maybe the guy who checks your water meter, once warned, "Tell a dream, lose a reader". Presumably this axiom only applies if you tell the dream in writing. If you tell it verbally, then your sum total of readers will probably remain static, unless a reader happens to be eavesdropping and becomes disillusioned with you after hearing about that recurring dream in which you are making out with a purple gibbon on top of a combine harvester.
"Tell a dream, lose a reader." It's one of those golden rules of writing that get trotted out all the time, and like most golden rules it makes as much sense as a beak on grizzly bear. I mean, "lose a reader"? Who gives a shit? Unless you only have one to begin with, I doubt losing a reader - especially a reader who is obviously such a prissy git anyway - is going to make much difference to your reputation.
Imagine what Coleridge, whose most famous poem allegedly came to him in a dream, would say if you told him not to tell a dream because - oh no! - you might lose a reader. He'd probably tell you to bugger off, or maybe ask you for some spare change so he could go buy some smack.
What if it's a really hot dream? I'd take my better dreams over novels any day, and I bet Henry James would have too, although his dreams were probably all repressed and airless whereas mine are liberated and exhilarating, albeit mostly about making out with purple gibbons on top of combine harvesters. But surely there is a market for that kind of thing? No?
In summary, Henry James or whoever - can somebody Google this? I don't have time - is wrong. Dreams are important to fiction of all kinds, including literature. A case in point: I Dream of Jeannie. I dreamed of Jeannie too, and it gave me more pleasure than reading The Portrait of a Lady. Except for the bit where the lady "does" Boston. That was pretty hot.