What's the recommended sleeping time for your pet?

I mean...people are supposed to sleep 8 or so hours every night in order to function properly. So, how long should your dog or cat sleep?

Most of the time, when I come across my dog or cat, they're sleeping...and, I know they sleep through the night too -- or most of it. So, do they need all this sleep or are they just lazy?

If they stayed up playing fetch all night, like if I stay up all night playing PlayStation...would their bark or meow be off the next day?