It's not anthropomorphizing to realize that mammals have a lot of physiology in common. If a dog scientist tells me that sleeping patterns are completely irrelevant for dogs because of some peculiar evolutionary adaptation, I'll believe it. But failing that, a decent null hypothesis is that it's probably pretty similar to humans (notice that my post started with "I'd imagine", not "It is a fact").

Also, just because X might be optimal for a pet doesn't mean that you have to do it. There's always something more you can do for your pet, but perfection is never possible.

And also, your incredible examples of confounding variables are not insurmountable, since sleeping patterns are successfully measured in humans even in suboptimal scenarios. Don't let the perfect be the enemy of the good!