Cat sleeping patterns

Nobody is sure why cats sleep so much. Cats evolved from a long line of hunters and predators?

Most wild cats use huge amounts of energy when they hunt and they need to conserve energy in between their hunting activity. When a cat (or any living thing for that matter) sleeps, it uses very little energy. The longer a cat sleeps, the more energy it conserves and the less often it has to hunt. Although today's domestic cats don't really need to hunt, their genes are still the same as before we took them into our homes as pets. - http://www.rambhai.com/Miscellaneous/cat-breeds

Sleep is a vital part of a cat's life. Proper attention to the sleeping needs of your cat will ensure that he grows, develops and matures in a satisfactory manner. - http://postonfire.com/Pets/cat_diseases