"The notebook and pen are professional equipment, as it were. Though actually there is something druglike about them, in the sense that their main purpose is to make me feel better. I hardly ever go back and read stuff I write down in notebooks. It's just that if I can't write things down, worrying about remembering one idea gets in the way of having the next. Pen and paper wick ideas."
Although, I find that most of the time I toss-and-turn b/c my mind is continuously thinking about solving some problem at hand. It's 3am and I should go to bed, otherwise I'll be a zombie at the office tomorrow, but there is this problem that I have to stop thinking about first. Creativity doesn't really follow the same schedules as "business hours"; I would suggest that if you can, stay awake thinking/working/doing until you can't anymore.