I have certain times of the month where I see visions. They're sometimes prophetic, I think, but perhaps only in hindsight. Also, I'm good at deduction, so maybe my subconscious is just taking the daisy chain a step further.
Mostly seem to be allegorical. I always wake up and have some big intellectual leap, tho. It's like my brain is slightly rearranged and some Eureka moment happens.