Close your eyes. No, actually; DON'T.
This is the second time that this has happened to me. I was LD'ing, and at one time I wanted my close my dream eyes for a second. (was trying to make my leap out of the window more dramatic I guess)
but it woke me up instantly! What happened? I think that moving my eyes (opening/closing) caused my real eyes to open... Maybe that woke me up?
It has happened before... Even though I could see the dream world I had the feeling that my eyes were closed (perhaps I could feel my real eyes?) so I opened them. Bad move.
Any ideas?