Dreaming.. yet not asleep

I know a lot of people have this, and it's very interesting to me. A couple nights ago I was drifting to sleep, and was very close to dreaming. So close, actually, that I was dreaming but I had not gone through SP yet. I could feel everything, and I could even open my eyes. Though opening my eyes would stop the dreaming, if I closed them for a minute it'd come back. It was weird. It felt like I needed to open my eyes in the dream, even though I could see, and when I did my real eyes opened. The dream was usually in thirdperson, watching more than taking a part in it, but I could change things such as the location.

Why does this happen? I'm assuming it's from being overtired and your mind falls asleep faster than your body, right? I must've been really tired to go right into REM.

i had this happen to me sort of...i was driftin off to sleep and i could open my eyes and everything but i was dreaming at the same time, it was wierd