Unable to open eyes and move body (except arms) while falling asleep?

I've already ruled out sleep paralysis. My hearing just cut off on both sides and my heartbeat amplified, almost like a heart beating next to my ear. I was unable to open my eyes and move my body except lift my arms. A tight feeling came over my chest (almost like flexing but not flexing) and overall lasted about 6 seconds, but it happened twice almost back to back. I cannot for the life of my figure out what this is. The only idea I might have is that my dog moved at the moment my body was shutting down for sleep and caused my brain to wake up. Still doesn't explain why I was only able to move my arms :/