WHY this is different before I explain the rest:

I was able to sit up during the SP and the instant I did, I felt like I was being crushed and unable to scream.


Now let me give the details:

I have the flu, and this was the first time in my life I have fallen asleep on my back.

So I awake in my room, BUT when I look up, my posters on the wall are upside down. Right away I know I am in trouble and have a huge rush of terrified feelings. All the photographs on my room are upside-down as I look around.
Next, I feel the sheets of my bed start to tighten around my body and sharp pains in my arms.
I try to fight, almost getting an arm out from under the sheets but they tighten more.
Finally I squeeze my arm out and sit up as fast as possible (I know this should wake me up).
HOWEVER, I do not awaken! Instantly I feel like my chest is being crushed from all sides and I can't scream. I massive black presence starts to rise in front of me, trying to show its face, but for some reason I can't see it. I sit there trying to scream over and over.

Finally I awake. I could not sleep after this...