We LIVE in colour...why wouldn't we dream in it?

I have to wonder at people who come up with baseless generalizations like, "Everyone who....". NOT the Op, obviously...but however these silly rumours get started, you've got to marvel at an individual's refusal to check into scientific understanding of a topic, before they invent an entire fabrication around an idea.

Science admits it knows relatively little about how our brains, and therefore a complex function like sleep, actually works. So, sweeping generalizations about anything like that should be dismissed.