As a cat owner, you may have noticed that your cat may walk up to you and sniff your face whether you’re awake or asleep. This odd behavior isn’t because your cat wants to annoy you but because cats generally sniff each other’s face as a way of recognizing each other.
Since a cat’s sense of smell is much sharper than a human’s sense of smell, cats sniff each other’s faces to recognize each other. So when your cat sniffs your face, it’s just verifying that it’s you. Annoying you in the process is simply a bonus.