It’s meant to be read aloud at bedtime. The narrator is trying to wax poetic about all the animals who are also going to sleep, but keeps getting interrupted by various nocturnal animals getting up to antics spoiling the go-to-sleep message. By the end of the book all the night-time animals are having a party. It ends with a question, asking how the listener can know it’s not all true, since they’re asleep? The illustrations give a lot of personality to the animals, and invited kids to open their imaginations to what goes on when they’re asleep. Who’s to know?