You've probably seen it before: a cat fit snug inside a small, nondescript box or another such tiny place. Whether you've spotted it in an adorable video online or you witness such behavior in your own home, finding a cat resting in a small space is not at all uncommon, and is a behavior that extends to even outdoor and feral felines. As much as we may like to believe that they are just doing so to create the perfect photo opportunities, it's obvious they like fit into small spots for other reasons. But what are those reasons?
Cats are well-known for being predators, as evidenced by the instinctual need to stalk, chase, and hunt pretty much anything that moves, be it in the great outdoors or inside your own living room. What people tend to forget, however, is that although most cats are exceptional hunters, all cats are still relatively small in size, especially when compared to their natural predators. For this reason, cats might be drawn toward tight spaces as a means to protect themselves from potential harm.
Not only does settling into a nice hiding spot keep them out of harm's way, having to curl up into that limited spaces forces them to keep their bellies, which is among the most vulnerable spots on the body, covered and safe from exposure. By keeping their vital organs hidden, cats are better able to rest easy. This trait serves outdoor cats for obvious reasons, but the fact that indoor felines still express such behavior suggests that the trait has been hard-wired from their pre-domestication days.
In addition to protecting their most precious body parts, sleeping in a tight position allows for quicker and more effective movement should your cat need to flee her once-safe confines. By sleeping with her limbs underneath her body and close together, the need to readjust her body in the face of danger becomes a non-issue, as she's already in the perfect position to activate herself forward and run toward safer spaces. A cat sprawled out on her side or resting in a curled-up shape may suggest comfort and ease with their environment. That's not to say that all cats sleeping with their legs underneath them are anticipating the worst — like people, some cats may just have a preferred position to sleep in.
While some instances may suggest that your cat is sleeping with one eye open, so to speak, other situations may be attributed to the comfort factor your feline is seeking. According to Chewy, some behaviorists believe that cats use small spaces as a source of comfort, both physically and mentally. Obviously, feeling safe and secure in your environment is comforting in itself, but it could be possible that cats use limited confines as a way to thermoregulate their body temperature. In the same way that we would curl up under a blanket to stay warm, a cat may be squeezing himself into a small ball as a way to contain their body heat, which becomes quickly reflected back at them when the space around them is small.
It is also possible that the smallness of a space can be comforting in the same way that a hug is comforting, enveloping a cat's body and providing a sense of security. This is the same logic applied behind items like the Thundershirt, which is a vest made of lightweight but firm material that wraps around a dog to offer them a sense of security in otherwise frightening or anxiety-inducing situations, like thunderstorms, fireworks, or being left alone.
Finally, you may find a cat, especially a young cat or kitten, inserting themselves in tight spaces for the sake of curiosity and play, as cats are well-known for their tendencies to seek out new places and things.