Whether you have pets or not, it's likely that you're aware of how much cats sleep on a regular basis. A typical house cat will sleep up to about 16 hours per day. Compared with the 8 hours or so that a human typically sleeps, this is a much higher percentage of your pet's life and of the day. It's unclear exactly as to why cats sleep so much, but there are a few potential reasons that scientists and veterinarians have to partially explain this behavior. Most of these reasons have to do with evolutionary changes that have influenced cats for hundreds of thousands of years.
Predatory Lifestyle
Cats in the wild are predators. House cats are no exception, as anyone with a cat that has caught a bird or a mouse can attest. However, because most smaller cats are domesticated at this point, they've lost many of the standard hunting behaviors that they developed throughout their evolutionary period. As a predator, your cat will be most active when his prey is most active, and traditionally this has been in the hours around dawn and dusk. This leaves the rest of the night and the rest of the day as times when food is less plentiful, and cats use the time to sleep and regain energy.
Because of the nature of the hunt, a cat must expend a lot of energy at one time in order to track, capture and kill its food. This means that, historically, cats have opted to save up as much energy as possible when they aren't actively hunting so that they'll have a better chance of catching and eating the food that they need when the opportunity does arise.
Diet
Another element of the predatory lifestyle that may influence the way that cats sleep is the fact that predators eat high protein diets that are rich in nutrients. This is very different from herbivores and other animals that must eat a large quantity of food that is lower in nutrient density. Because of the rich nature of the meat that cats have eaten throughout their history, they can afford to spend less time eating and more time sleeping.
Boredom
Many domestic cats spend a good portion of their time sleeping simply out of boredom. Cats are intelligent animals that thrive on visual and other types of stimulation. If left alone in a home, cats will generally become very bored quite quickly. Even if you or other people are present in the home while a cat is there, the cat will not continue to be entertained unless you actively work to engage it. If you're looking to have your cat spend less time sleeping, try playing with him and engaging him in other ways to keep him excited. Still, it's important to be mindful that cats must spend the majority of their time sleeping because that's how they've developed.