You could always keep a recorder, or a dumbphone in record mode, next to the bed, sound-activated*.

I did that once and I had the most amazing dream that I just had to record for posterity, so I blurted it out before it was lost forever. The next morning, I played it back, excited to recall just what life-changing insight I'd experienced, and to transcribe it so as to share it with the world.

It was "Blurble bub garble snortle snurk..."

*only works if you don't snore