you may not be moving around during sleep. I too used to fall asleep very quickly but wake up a few hours later with numb arms and pins and needles. I figured out that I wasn't moving around during sleep because I was at the end of my dopamine dose by the time it got to the middle of the night.
I take prolonged release pramipexole and madopar; I take the madopar during the day but leave the pramipexole for just before bedtime. This tops up the dopamine to enable me to have enough to move about during sleep. I haven't woken up with pins and needles in ages
hope this helps