Heh, I remember once I fell off a cliff and seriously FELT the "thump" at the bottom. In the morning I found out I fell out of my bunk. I was sore all day. >.O

But really, I think it IS possible to use this. There was some machine or something (don't remember what it was called) that would detect your rem-period and flash lights in your eyes which you were supposed to use as a dream sign. Aparently it worked for some people. (Or like me, you can take turns with your siblings and have them wake up at 3:00AM to flash a flashlight in your eyes.