Reading Comprehension
从下列每篇短文的问题后所给的四个选择项中选出一个最佳答案。

     Now, there is growing evidence that naps（小睡） are coming back. Many companies have set up nap rooms with beds, blankets and alarm clocks because they have recognized that most of their employees do not have enough sleep. If labor unions are truly interested in worker welfare, they should make such facilities a necessary item in contract negotiation.
     A brief nap makes people feel refreshed and relaxed. If workers take advantage of the opportunity to sleep for twenty minutes or so during the workday, they can go back to work with renewed enthusiasm and energy. Dr. Linda Pitt, for example, often manages to take a ten-minute nap between patients. She says that this respite helps her focus better on each patient's problems. Also, there are companies that encourage their employees to take naps. They find that napping reduces accidents and errors and increases productivity, even if it shortens the workday a bit. A recent NASA study showed that twenty-four-minute naps greatly improved a pilot's alertness and performance on long-distance flights.
     Studies have found that sleepy workers make more mistakes and cause more accidents. They are more likely to have heart attacks and other physical disorders. Dr. David Jones, a sleep researcher at Harvard, explained that the brain becomes less active when it fails to get enough sleep. It has been proved that lack of sleep affects attention and performance. It often leads to "microsleeps", that is, involuntary lapses into sleep. These "microsleeps"often cause accidents. He suggested taking a"power nap"during the day to prevent the effects of sleep loss.
     "Naps greatly strengthen the ability to pay close attention to details and to make critical decisions," added Dr. Jones. He also stated that"a nap taken about eight hours after you wake can do much more for you than if you add those twenty minutes onto already adequate sleep at night."