It seems Kitty can sleep anywhere, anytime. Since he can easily sleep with the TV on, you may think he can tune out noises in his sleep. This is only partially true. He actually just employs the same mechanism that many teenagers do: selective hearing.
Kitty sleeps a lot. More than most other mammals. He can clock up to 18 hours a day snoozing. However, he doesn't sleep like we do, settling down for a period of uninterrupted sleep at night. He naps several times throughout the day and is more active at night. This is adopted from his wild brethren, who hunt at night. A house cat may choose to sleep at night because it's a time when the house is nice and quiet or perhaps while you're away at work. He'll probably choose a warm, comfortable spot he can nap but still keep tabs on his family.
Cats have a superb sense of hearing. While his threshold for low sounds is about the same as humans, his ability to hear high-pitched sounds is superior. A human's high-end is around 20 kHz, but Kitty can hear about 65 kHz. This means he can hear the high-pitched squeak of a mouse even if you can't. He'll respond more to female voices since they tend to be higher. Sometimes Kitty will be peacefully dozing and startle awake, looking around surprised. This is because he probably heard a noise you couldn't and he snapped to attention. Once he decides nothing is amiss, he'll settle back to sleep.
One Ear Open
Kitty is keeping tabs on his territory even when he snoozes. Kitty has an understanding of which noises are normal and which are not. Noises he used to, like the dryer or dishwasher running, won't disturb his slumber. However, if he hears something that is out of the ordinary he'll wake up alert to check out what disturbed him. Sometimes this can be something that signals danger -- or perhaps you simply filled his food bowl.
Since Kitty is naturally nocturnal, meaning he's up at night, he's ability to jolt awake at the slightest noise is a good defense mechanism. When your cat is sleeping, he's pretty vulnerable. Since he sleeps during the day, he's easy pickings to predators who hunt during the daylight. While Kitty can go into deep sleep cycles, it's only for very short periods of time. You'll recognize this deep sleep, called REM or rapid eye movement, because he'll twitch his whiskers, ears and paws. Even then, he's ready to wake up in an instant in case he needs to flee from a potential predator.
- VetInfo: Understanding Cat Sleeping Patterns
- The Enyclopedia of The Cat; Michael Pollard
- Why Does My Cat Do That?; Catherine Davidson