Incidentally, I find that reasonably good insights can be remembered the next day, but only if some effort has been made to set them down another way. If I write the insight down or tell it to someone, then I can remember it with no assistance the following morning; but if I merely say to myself that I must make an effort to remember, I never do.
I find that most of the insights I achieve when high are into social issues, an area of creative scholarship very different from the one I am generally known for.