单项选择题

If you feel tired all the time, you don’t necessarily need to go to bed earlier -- the solution could he as simple as taking a five-minute afternoon nap.
Children under five have an abundance of energy and one of the reasons is because they nap once or twice a day. Many sleep experts think we’re programmed to take a nap during the day, and gating back into this habit can be a solution for those who feel tired all the time.
Prof. Chris Idzikowski of the Sleep Advisory and Assessment Center thinks that one can feel refreshed after just five minutes sleep. And research has shown that concentration and attention are improved after even a short nap.
Sleep is genetically programmed in babies and it’s only as we get older that we learn to sleep for about eight hours a night and not at all during the day. But most research suggests that we are not physically designed to sleep for one long, single block.
Before the working day became nine to five, all Western sleep patterns were more broken up. Research has shown that in the Middle Ages, people’s sleep quite often occurred in ’three distinct parts — a nap in the afternoon, an early morning nap and another, longer sleep until dawn.
So if you do find yourself feeling sleepy through the day, don’t feel you’re being lazy by giving in to sleep and having a nap. Your increased energy and alertness will make the rest of your day extra productive.
What happened to the westerners since the working day became nine to five