Numb fretting hand

What about the action of your guitar ? It might be unusually high !

You're likely getting nerve compression in your wrist, like Carpal Tunnel Syndrome. Check your playing position. Your wrist doesn't like to be bent over sharply while fretting. Get the guitar neck up high, parallel to the body, and your arm out to the side. The closer you get to the classical guitarists' position, the better. Trying to play low-slung guitars has given many players grief. Relax your hand and wrist as much as you can.

Old fogeys like me are prone to getting hand numbness even if they're doing it right. I can play mainly slide a lot longer than I can fret.

I don't think the action is it...but I have an acoustic so there isn't much I could do about it heh....Thanks though

it sounds like swelling of the muscle group you are using to fret. the swelling pinches the nervce which gives you those symtoms.

you muscles will strengthen and the problem could subside.
otherwise, dont play for such a long time. give your hand a rest and slowly work back to longer practice sessions.
if this persists see a doctor.

Personally I'm occasionally getting a nasty twinge in the back of my fretting hand when I'm working on three or so barre chords. (Sister Golden Hair - C#m, G#m,F#m and the A) And when I started I also was getting a certain degree of pain in the fretting hand. Of course I'm a bit older (40's) and I know better than to just 'push through the pain'. I back off a bit in whatever is causing the pain. This requires paying close attention to what is causing the pain so you can back off on whatever it is that is causing pain while still getting practice in on other things. For swelling I use Naproxen, which is Aleve I think. And when all else fails there is that doctor thing.