The passage tells us that cats ______.

Cats are creatures of habit.  They like to go to sleep about the same time everyday and for a certain length of time. They seem to have a natural clock inside them that tells them when to sleep.
   Cats supplement their regular sleep with occasional catnaps. Some experts feel that humans could also benefit from this habit. Catnaps help to build up energy in the body. They are also a good way to overcome boredom. Since cats have moods similar to those of humans, some experts believe that people can improve their moods and attitudes by catnapping. People might become happier.
   A number of famous people have copied cats by taking catnaps during the day. The naps would usually last from 15 to 30 minutes. Winston Churchill took catnaps. So did President Harry Truman, John Kennedy and so on. These famous people were known for their energy. They were also able to work long hours, often late into the night. And napping was their secret. Perhaps more people could learn from cats and take naps to feel better and live longer.