Does your cat prefer to sleep on its side? A recent study has found that nearly two-thirds of domestic cats prefer to sleep on their left side. This isn't a random coincidence but is linked to cats' complex survival instincts.
The research, published in Current Biology, was led by Dr. Sevim Isparta from the University of Bari Aldo Moro in Italy, with contributions from an international team including researchers from Ruhr University Bochum, the University of Prince Edward Island (UPEI), and other institutions across Germany, Canada, Switzerland, and Turkey.
Study Methodology
To investigate this phenomenon, the research team analyzed 408 publicly available YouTube videos of sleeping cats. The videos were selected based on specific criteria: they had to be unedited, unmirrored, and clearly show a single cat in a sleeping position for at least 10 seconds, with its entire body visible.
The results showed a clear preference: 266 cats (approximately 65.1%) chose to sleep on their left side, while only 142 cats (about 34.8%) slept on their right side. This significant difference led researchers to conclude that the leftward bias is not coincidental.
Why the Leftward Bias? An Evolutionary Advantage
The study suggests that this preference is an evolutionary survival strategy. It's believed to be connected to the specialized functions of the brain's hemispheres in mammals.
- For most mammals, the right hemisphere of the brain is primarily responsible for processing threats, spatial awareness, and coordinating rapid escape responses.
- When a cat sleeps on its left side, its left visual field remains unobstructed. The visual information from the left eye is directly processed by the right hemisphere of the brain.
Cats are known to prefer sleeping in elevated positions, which helps them spot predators from below. When a cat sleeps on its left side, its left eye can face potential threats approaching from below. If a threat is detected, the visual signal from the left eye is quickly sent to the right brain, allowing the cat to swiftly assess the risk and decide whether to flee or defend itself, acting like an automatic alarm system.
Cats sleep between 12 and 16 hours a day, meaning they spend approximately 60% to 65% of their lives in a vulnerable, low-defense state. Therefore, this "left-side sleeping" strategy allows them to remain vigilant and ready to react to danger, even while resting.
So, the next time you see your cat comfortably lounging on its left side, especially by a window, remember that this seemingly adorable posture is a highly evolved survival tactic refined over millions of years.
Source: Lateralized sleeping positions in domestic cats: Current Biology
