Your sitting position can effect your hands. Vertibrae C5 through C8 (your neck area) may be out of line or being pinched, this can cause you to feel sensations in the hands. Yoga exercises/stretches are good for relaxing this area. The trapezius muscle which helps to hold the head up is a "tonic" muscle, meaning it is "on" all the time during waking hours, hopefully it relaxes while you sleep. If it does not turn off while sleeping it will give you that stiff neck feeling, this can also cause sensations in the hands. I have had clients who have had problems with their hand while meditating, stretching and massage has helped.
Don't know if this is your problem, but it might be something to look into. Hope this helps.