Recently I have experienced an unusual numbness in my palms. It has happened while stoned, but I recall instances where I was completely sober and lost sensation on the surface of my palms.

I know that one's palms serve a vital spiritual purpose and I am wondering if this is anything to be concerned about. Also, during bouts of meditation or yoga I experience heat resonating from my palms, but I know this is normal.

tl;dr why do my palms go numb sometimes?