It use to happen several times, but it was long ago. I never knew what it was, and I start to wonder if it could be sleep paralysis.

Here is what happen : I'm about to fall asleep and it's looke like i'm plunging into my bed. My eyes start closingthe same idea always cross my mind when it happen : If you let yourself go, you will never wake up. So I try to move my arms, my legs or to shake my entire body, but i'm blocked. And finaly i manage to move my head and i'm free to go.