When Bathroom and Sleeping Habits Become One (sort of)

Our elderly kitty has severe kidney problems. We give her subcutaneous fluids twice a week and epogen shots weekly (for her anemia), but she's very thin and rather weak. We think this was why, for several weeks recently, she was peeing wherever she happened to be sleeping. Since then, I've put all of her accoutrements (water dish, food, and litterbox) in my study. She uses the box now, and she also seems to be getting more peppy. However, despite having her own plush kitty bed (which she had been using) and a comfy futon on which to lie, she spends almost all day and all night sleeping in her litterbox--even when it's dirty!!
My husband and I try to tell her that it's unsanitary and gross (yeah, like one can be rational with a cat!), and we try to encourage her to sleep in a more comfy place. But she's determined.
Has anyone else had this situation?

When was the last time she was vet checked? As for her sleeping habit, this can happen for cats with CRF towards the end of their years. I would perhaps add another litter pan for her with clean litter and see if that helps the situation. I know before we had to make the tough decision with Bravo, he was sleeping in the litterbox all the time.

Hissy,
Thanks so much for sharing your experience with an RD kitty; it helped a lot to know that we shouldn't worry too much that Echelle sleeps in her litter box. I'm so sorry you lost your beloved Bravo to this disease!