I've heard that drinking some amount of caffeine before sleeping will help you remain more alert and aware in your dreams...is that true? and why doesn't it just keep you up?

I use MILD to some extent...when I first lie down I tell myself I'll have an LD, I explain my dream signs to myself, etc...but at some point I have to do my best to think of nothing until the HI beings to kick in and I finally fall asleep. I've heard that MILD only works if you can keep thinking until the moment you fall asleep. is that true? and how can you fall asleep if you're maintaining a constant inner monologue?