Cat behavior/care

Question
My cat is very old 13 years and lives with my mother she is worried about him beacause all of a sudden he likes to sleep on the litter box, day and night unless he is eating, what's going on , is this normal, is he o.k.? He has had past probs with his kidneys but after a stay with the vet and rehydration via I.V. he was o.k. He also takes thyroid medicine for an overactive thyroid. My mother worries me by telling me that she thinks he is old and going senial, and that he is going to die soon (she has been saying that for years) recently she has said he's been hiding in dark places and now this litter box thing, I know my mother likes to worry me on purpose yet I'm still not sure why, but I need to know from a vet or somone with experience with older cats, is this litter box thing a sign of something else going on, and should I be worried?  

Answer
Hello Trinity,
Sorry to hear of you mother's kitty's problems.  You are right when you say you need advice from a vet.  I'm sure there are vets on this board to better answer this question.  Based on my experience with cats, I would suggest that she take him into the vet for a check up.  Male cats are more prone to kidney issues, and this sounds like there may be some reacurring urinary tract problem.
If this were my cat, I would take him into the vet as soon as I could.
I hope things work out for him (and your mother).
Thank you,
Tomay