Cats’ Left-Side Sleeping Habit May Be Linked to Survival

Cats have a strong preference for sleeping on their left side, a behavior that may have evolutionary benefits, according to a study conducted by an international research team. The researchers analyzed hundreds of YouTube videos of cats sleeping and found that about two-thirds of them favored sleeping on their left side. This side preference may be linked to the brain’s hemispheric division of tasks. When cats sleep on their left side and wake up, their left visual field, which is processed by the right hemisphere of the brain, provides them with better spatial awareness and a quicker response to potential threats or prey. This enhanced threat detection and rapid escape response could have helped cats survive in the wild. The study, conducted by researchers from institutions in Italy, Germany, Canada, Switzerland, and Turkey, suggests that this behavior could be a survival strategy ingrained in cats over time. The research was published in the journal *Current Biology* on June 23, 2025.