Is this a state of REM? Or a medical problem?

Although I am sure there is some technical or medical term for this, I have always referred to it personally as "limbo" land. I believe your mind wakes a bit before your body does, and you freak because you have no control, which causes the gasping. I did this a lot when I was sleep deprived after having my children. I remember opening my eyes a bit, and trying to yell or move, but I couldn't, but finally I woke up and could move again. It's very unsettling to say the least.