I had that too. I would pass out and get these jerks when I woke up. My dr told me it was because my body was so exhausted it would get into a state of "relaxation" even though it doesnt feel like it, and then I subconsiously wake up with a bad shake. Its so scary not remembering what happens. I would be in the middle of a sentence and id fade away and when I came awake again I had no recollection of what happened. I was on heavy narcotics after a surgery plus neurontin, baclofen, tramadol, etc plus the others. Its scary. What meds are you taking right now??