If you have had sleep paralysis stuff in the past, it could just be a muscle tone thing. You come out of REM sleep with zero muscle tone and then your body takes a while to find a new equalibrium as you wake up.

I doubt whether it is waking you up, but more a function of waking up. It may be diet related. Maybe Magnesium deficiency?

Muscle spasms, muscle cramps, muscle jerks, muscle tics, eye tics, hiccups can all be caused by a magnesium deficiency. Magnesium and calcium work together to control muscle action. Calcium tenses (tightens) the muscles; magnesium relaxes the muscles. With insufficient magnesium the muscles stay tense, causing a cramp in the muscle. This could happen when you have too much calcium and too little magnesium.