zombies don't breath...sleep

As I somewhat know zombies. They're dead creatures. No souls...or anything. They just rely on instinct. Zombies don't breath...sleep..or anything that a human usually does. I have seen this movie few times before. And wonder if the director...writers and producers actually know what zombies do when they're dead? Or turned into zombies. Zombie don't sleep....breath...or even see who they're eating. They just rely on instincts. Just dead creatures opposite from who they were before. Since they turned zombie. They're human feelings...and memories has gone. When I was watching the survivors sneaking thru the slumbering zombies. I thought...This is a horrible zombie movie.