This is the reason why cats sleep on their left side: The research behind your pet’s sleeping habits
Ever wondered why your feline friends sleep the way they do? Here’s why.
Whether it’s in a cardboard box, bathroom sink, upside down, or in your boots, cats and their silly sleeping habits have fascinated us for years.
And it gets better: their peculiar positions might be cuter than we think—and science now backs it up. A new study published in Current Biology suggests that domestic cats actually prefer snoozing on their left side. But why?
It seems evolution has wired them to stay alert even while dreaming.
Researchers, including teams from Italy and Germany, dug through 408 YouTube clips of cats napping on their sides for at least ten seconds. The result? Roughly two-thirds favoured curling up left-side-down.
In a fascinating showing of science: their position isn’t random. When cats sleep on their left side, their left eye remains unburied and their right brain hemisphere remains primed. That brain side is key: it processes spatial awareness, threat detection, and rapid escapes. So, if a predator—or a noisy vacuum—beckons, cats can spring into action faster.
The study authors explained that “since cats prefer to sleep in elevated positions, upon awakening they would immediately see predators or prey with the left side of their visual field. Since the right hemisphere has advanced spatial abilities and can quickly coordinate rapid escape and possibly also hunting functions, left-side sleeping would provide evolutionary benefits as a survival strategy.”
“Sleep is one of the most vulnerable states for an animal,” the study explains, “as anti-predator vigilance is drastically reduced, especially in deep sleeping phases.”
“Therefore,“ it adds, ”they spend almost 60–65% of their lifetime in a highly vulnerable state. To reduce predation risks, cats prefer to rest in elevated positions so that predators are more visible to them and the cats, in turn, are more visually concealed from predators."
Summary extract:
For example, the right hemisphere excels in processing threat-related stimuli, providing the left visual field an advantage in reacting to a predator approaching from the left3. Here, we report that two-thirds of cats prefer a leftward sleeping position, giving their left visual field and thus their right brain half a privileged view of approaching animals without being obstructed by their own body.
- https://www.sciencedirect.com
Funny 🤣 pic.twitter.com/N7NeCeXFLx
— Cats with pawerful aura (@AuraWithCat) July 19, 2025
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