Not so often but about 1 time per week I wake up in some kind of paralysis, but I can move.

I can move really really slowly with a lot of effort, after I move let's say my hand for a few cm I can move fully again, but after I rest for few seconds I get back into that state,and usually I just go back to sleep and after that I wake normally.

So, what is it?
It could be dream but I don't think so...