How Do Bears Hibernate?

I read once that large bears can hibernate fir up to 7 months, in which time they do not eat , not sure if they have to drink, Anyway, how do they avoid uremic poisoning? Even at rest, the body generates waste products which must be gotten rid of. Have scientists discovered how bears do this? And, do bears sleep contniuosly while they hibernate? This would be a useful adaption for humans-could we adapt to hibernation?

I have absolutely no personal expertise in this, but here are a few links to assist you/get you started:

Hibernation and waste products in black bears

Human hibernation