numbness in arms and legs

I find that I need to avoid certain positions and situations to minimize this nice little feature of the disease. It's been so bad at times that I've had to look down, as I'm trying to get up, to make sure my legs/feet were actually on the ground after sitting on a bar stool for half hour or so. No numbness or tingling, just feels like my legs/feet aren't there at all. Can happen with my arms/hands as well.