One specific habit has been highlighted by scientists: many cats prefer to sleep on their left side. You might be wondering why… Well, according to science there actually could be a good reason.
If you are a fellow cat owner, you would know that cats sleep – a lot. And, people seem to love to capture these moments, and share them with the world. Researchers from Europe and Canada used this to their advantage, and analysed 408 videos of sleeping cats, and found that in two-thirds of them, the left side was favoured.
This is actually quite common amongst most animals, who have a consistent preference for one side of the body. This is known as behavioural lateralisation. It is seen amongst humans, where most people are right handed. Whilst most kangaroos are left-handed.
Vertebrate brains have a left and a right side, they are referred to as hemispheres
Interestingly, brains are also lateralised, both physically and functionally. Vertebrate brains have a left and a right side, they are referred to as hemispheres, both hemispheres work together but they also have separate specialisations. In humans, the left hemisphere plays a dominant role in processing language, whereas the right hemisphere deals with visual elements like shapes.
Also, the opposite side of the brain controls the opposite side of the body, so the right hemisphere controls the left side of the body and vice versa. This is because nerve fibres cross over at the base of the brain when they travel from the brain to the body.
When cats wake from their well-deserved cat-nap, on the left side they see a left visual field of view that is processed by the right side of the brain. The right hemisphere in cats is responsible for spatial awareness which processes threats, and can coordinate rapid movements – often produced by cats.
their survival depended on the ability to quickly avoid danger when they woke.
Unsurprisingly, this instinct leads back to their ancestors. Those who were undomesticated, and would therefore their naps were out in the wild. Here, their survival depended on the ability to quickly avoid danger when they woke. Sleeping on their left side activated this ability (the right hemisphere), increasing their chance of survival.
Ultimately domestic cats have inherited this trait. Although it is less likely they are going to get pounced on by prey, there is still potential danger, especially when they are outside exploring.
It also makes sense as to why cats can switch from being passed out, dead to the world to suddenly awake, and alert gulfing down their dinner. Since the right hemisphere also reacts faster to emotionally arousing objects like toys, fast-moving prey, and food – of course.
So, the next time you see a cat snoozing on its left side, don’t forget that underneath all of that fluff, is a finely curated predator ready to pounce.