I was experiencing this same symptom. I attribute it to increased spasticity. I also noticed that in the morning when I stretched my arms above my head, my knees drew up as if I was a marionette.

Stretching in the AM was painful. And yet, I had difficulty walking because my knees locked so I walk like Frankenstein's monster.

The CCSVI procedure has taken away the sleep problem of turning into the extreme fetal position. I also do not act like a puppet anymore.