I've written music (and solved other problems) while sleeping, but it's not a "dream". It's not visual at all, it materializes as music stuck in my head. My belief is that all of my best music comes from an unconscious place. I understand theory passably well, and can mechanically produce music from the principles of western music. But my best stuff doesn't happen like that. It just...appears as melodies and harmonies. Sometimes when sleeping, but often not. When awake, it helps if I'm holding a guitar since then I can translate what I'm hearing to something tangible. Quite often I'll listen to something the next day and wonder where in the world THAT came from. It's a mystery. Music also appears somewhat magically while walking, driving, or in the shower. I'm not alone in this, but I don't think it's common, and wouldn't know how to teach it.

I do dream vividly, but It's not musical. Mostly variations of common dreams like it's final exam week and I forgot to go to class during the term. That one never gets old...

DC Ron
BiaB Audiophile
Presonus Studio One
StudioCat DAW dual screen
Presonus Faderport 16
Too many guitars (is that a thing?)