I can't speak for your condition but I take pregablin for fibromyalgia and have been sold it's similar to gabapentin (please correct me if I'm wrong someone).
It initially made me very drowsy, I felt drunk at first (though in a good way!) then pretty dozy and muzzy headed though it definitely took my mind off the pain, it was actually quite a nice comfort thing, just to be happily dozy :) I had to adjust a bit at work initially as I couldn't think or do things as fast but that has reduced over time and I don't notice anything now drowsiness wise. If you drive or do anything where it could be dangerous then do be careful initially, depending on dose, frequency etc...
I really hope it helps for you :)