I have that.It was really getting bad, I could hardly hold up my books in bed. Went to doctor. Mine is carpal tunnel.She has me assuming, a 'neutral wrist" position, when I ride, if it gets numb( and anywhere else). I find myself riding with one hand, the other in my lap with wrist straight, until it gets feeling.
That helped, as did training myself to take more weight on feet and butt,but what helped the most was paying for fit on the bike . It turned out that I was about 5 cm too far up ! Now its much better. I feel like a old granny sitting up so far, but now hands much better.
Conquering illness, one step at time.