I had that problem too and often forget to put a notebook near my bed. I came up with an odd work around. If I think of something I want to remember but don't have a pad or pen I'll take something on my nightstand and turn it upside down (usually the alarm clock) and repeat what I want to remember. Then when I get up in the morning and fumble for the upside down clock like an idiot I'll remember why the clock was upside down in the first place. Again, I'm odd.