A mate of mine mentioned to me the other day a weird thing i'd never before heard of. Apparently there's a technique which can be used to realise your dreams in the waking state. If, as you're going to sleep, you raise an arm, you can actually fall asleep with the arm still raised. But soon after, the arm will drop, waking you up, and apparently with the awakening comes a strange waking dream experience.

I don't really know how this works. Maybe sleeping with your body still slightly physically active causes a lighter sleep or something. Has anyone heard of this before, and know what it does and how?