I think old cats do sleep a little more, but cats in general sleep around 18 hours a day anyway, which is crazy compared to humans.
Old cats do indeed sleep more,
but what we know is that when a cat is unwell, they pass the time by sleeping. A lot of the old wisdom about old cats sleeping all the time comes from before we realised how much old cats suffered from arthritis (80% of cats over 8 years old or something). Put an old kitty on anti-inflammatories for two weeks, and if they start jumping on chairs and going outside again, they weren't sleeping "because they're old" but because it hurt to move around.
When I started taking my cat behaviour classes, it chipped even more at this received wisdom. I've
written about it in French on my blog, but basically, the default behaviour of the unwell cat is to sleep. This makes it a very practical pet, because it can take a lot of passive abuse without bothering us. Not saying cat owners knowingly abuse their kitties, but after discussing with the vet who was giving the course, I came out horrified at how much unknowing abuse there is going on with cats, particularly cats kept in environments which are way too poor for their needs as small predators (tiny flats, alone most of the day, locked out of the bedroom at night). His guideline is that a healthy cat should have at least 4-6 hours of activity a day: "hunting" for food and other hunting-related behaviors (watching cars go by on a busy road is fine), eating, grooming, playing, socialising. Most cats never get anywhere near that.
Old cats, clearly, have different needs. But they still need more activity than we imagine, and it's not that they're sleeping so we shouldn't bother them, it's often more that they're sleeping because nothing interesting enough is going on. The course the vet is giving on old cats is in April, I'm really looking forward to it and hoping Quintus will still be around so he can benefit from what I will learn!
If you really need your cat to eat, wake them up and put them at the food bowl, I don't know if its instinct to wake up and eat or what, but it has worked really well.
Oh, definitely. I always do that with Quintus if he seems to not be eating enough or if I'm worried about his food intake. I know he's feeling poorly and his old paws hurt, so I gently pick him up from his nap and put him down in front of his bowl. Sometimes I need to pet him or find a way to get his nose closer to the food (lifting up his middle a little usually does the trick). When he was on kibble I would shake the kibble -- the interesting noise is stimulating. When Bagha was old I would shake the kibble around to make it move -- much tastier like that! (Even blind Quintus finds
moving kibble more interesting.)