My 13 year old cat WON'T use his litter tray at night unless I go with him. We are on the top floor of a 3 storey house and the litter tray is on the ground floor, so a 3am wake up call to take him to the litter tray is not good. If we don't take him downstairs, he either spends the next hour knocking things off surfaces until we do, or worse, wees where ever he likes. He sleeps with me every night, and I don't think I can change that at his age.....any other ideas??