You do not need the control of the physical body. When you are in the sleep paralysis mode, u should not try to move at all.
Instead you should relax, letting you to fall back into sleep and do phantom-finger moving for 10 seconds.
If you would like to learn more, visit:
http://research.obe4u.com/
They have an free to download PDF guide book (just make sure it is not the one for the teachers), and a youtube video.