Your relationship to the person on whom you are spying matters. If that person is your child or your employee, you have a lot more leeway when it comes to monitoring their activities. If you think someone is spying on you illegally, file a report with local law enforcement so they can investigate your case.
Most cats snooze around 16 hours per day. The majority of their sleep time, however, is much shorter than the typical seven hours or so that humans average at. night. Cats tend to sleep lightly, without going into a deep sleep.
Because they are on exceptionally good terms with it, I believe cats have much to teach us about the secrets of natural sleep. Cats commonly sleep between 12 and 16 hours a day -- more than most mammals and up to twice as much as humans. Why do they sleep so much? Well, because they can. Cats are predators with few natural enemies, meaning they live under the auspices of a generous, genetically-endowed sense of physical safety.