Cats conserve energy
Our feline friends are hardwired to give chase and hunt, mainly at night. In the wild, they need to do this to survive, and all that stalking, chasing and killing burns a lot of energy. House cats still have this wild streak, and even when playing will stalk and pounce on prey in the garden or on toys around the house. Hunting takes a lot of energy, with short but very intense bursts of activity, so cats need plenty of sleep in between.