"Cats prefer to sleep on their left side. This is the conclusion drawn by an international research team that analyzed several hundred YouTube videos of sleeping cats. The researchers see this bias as an evolutionary advantage because it favors hunting and escape behavior after waking up. The team from the University of Bari Aldo Moro (Italy), Ruhr University Bochum, Medical School Hamburg and other partners in Germany, Canada, Switzerland and Turkey report on the study in the journal Current Biology, published online on June 23, 2025."
https://www.sciencedaily.com/releases/2025/06/250626081533.htm
