[driverdan]

This doesn't happen for everyone. I've never had this happen. I've had a few dreams that seemed like amazing insights when I first woke up but then realized how they were dumb dream ideas.

That said solving problems while not focusing them has been repeatedly shown in research, including in dreams. I've had it happen many times while awake. The technique is to work intensely on a problem, then completely stop and move to something unrelated and simple. Often times a solution or missing information will pop into your head much later.