‘A dream unquestioned is a letter unopened’. Apparently. Do you agree?

Twenty years ago I was in the grip of prolonged and serious physical pain due to a then-undiagnosed condition. I couldn’t work as normal. I spent long periods confined to the house. Someone was very unkind to me and, as a way of acknowledging his fault without having to say it aloud, he handed me a book, saying I might find it of interest. I had plenty of time to read it thoroughly, footnotes and all and, in one of those, discovered a reference to a book that came to mind forcefully this morning.

I woke from a  dream so vivid and engaging that I was able to write down the dialogue between the figures in it and to describe their outward and inward dispositions, partly because I had ‘been’ them all, inhabiting the action from their perspectives. This is not possible in waking life. At least not with the immediate and assured access a dream affords.

This morning’s scenes, I realised, in which I was both multiply participant and also the observer, opened up for me a way to go deeper into a character in the novel I’m writing.

I wonder how common it is for writers to take advantage of what dreams offer?