What you described before this incident though, is sleep paralysis.
Here's a very simple, basic explanation:
When you go to sleep your body "disconnects" from your brain -since your brain is always active. If this didn't happen, you'd be sleep walking and physically living out the movements in your dreams. Needless to say, this will result in catastrophe.
So the voluntary impulses from the brain to the rest of your body "shuts down".
When you experience sleep paralysis, your brain actually wakes up, but your body remains "disconnected/asleep". It is then that you experience all these weird things. Anything from forces pushing, pulling, voices, sounds, hallucinations, presences, etc. You're awake, but your body isn't. You gain control once your body comes around and then everything weird stops.
I'm not saying what you experienced isn't real. It's very real to you, but there is an explanation. I'd be more likely to believe it's something else if it wasn't for the fact that this always happens to you around bedtime, IE. just before, during or after you sleep. If this happened to you in broad daylight after you had a good night's rest -the previous night - then you might be on to something. Otherwise...you can bet your bottom dollar it's
most probably sleep paralysis.

(Well it usually is, 99% of the time

)