Over play sessions blood flow lowers to the fingers especially because of grip types. The carpal nerve plays a part, but blood flow is also a big issue. I have some very bad RSI/carpal tunnel/finger issues from overplaying competitive shooters back in the day with poor personal health practices.
However, it's better to just go wash your hands and stretch them out between rounds or whatever. When I started washing my hands it got better.
Also, to anyone who does have this issue, the same effect can be done by holding your hands in a bowl of ice cold (as in, RATHER cold) water until it starts to hurt a bit- but not so long you can get frostnip or anything. It will hurt, but when you take your hands out, the rush of warm blood flow from your radial artery to the inconsistently cold region of your body will stimulate bloodflow a good deal. It really does help a lot if you have hand pains etc. It feels INCREDIBLE. It's like taking a cold shower; it forces your body to heat itself and wakes you up rapidly.
This is a real issue especially for those with claw grips etc.