I experienced that repeatedly some 35 years ago after a long illness. It is scary at first. I could just barely speak, like the monster in Young Frankenstein. I would ask my housemate to wake me up. He would look terrified, but screw up his courage and shake me. That did the trick.
It eventually went away. No recurrences in decades.
"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln