I sometimes dream about a problem I've been trying to solve for a day or two. The dream usually gives me an 80-90% correct solution, I just need to connect some dots.
I still remember dreaming of a kernel config issue, reading the solution on a trains timetable in a train station.
I’ll dream up a solution to a problem that’s like 50% of the way there. The other half is like “let’s use this unicorn horn to guide us to the cause of the segfault”