If your cranky house cat always acts like they just woke up from a nap, it may be because they did. The average cat spends 16 to 20 hours of their day asleep. It isn't because they're lazy or bored with hanging out with you: Fluffy's tendency to doze the day away is baked into her genes.

Even if your cat is the least active member of your household, they still have the instincts of a predator. According to PetMD, house cats are hardwired like big cats, so they spend most of their time conserving energy in preparation for a tiring chase and hunt. But in the case of your pet, "hunting" probably entails pouncing on your shoulder or wrestling with a toy after a long nap.

Because of their sleep schedules, cats may seem especially lazy to their humans. Cats are crepuscular, which the Oakland Veterinary Referral Services defines as being active around dawn and twilight. In the wild, this keeps cats from crossing paths with big predators that hunt during the day and nighttime. In your house, it means your cat is asleep during the daylight hours when you may be working.

While cats do sleep a lot, they don't sleep particularly deeply. A sleeping predator has to be ready to spring awake in an instant, and when cats sleep, they position themselves in a way that allows them to transition into action as quickly as possibly. These lighter naps happen in 15- to 30-minute increments, while deeper rapid brain movement sleep lasts just 5 minutes. So if you want to stay on your kitty's good side, you may want to think twice about petting them during a cat nap.

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