Medical experts  say most Americans do not get enough sleep. They say more Americans need to take a nap--that is to rest for a short time in the middle of the day. They give people advice to sleep lightly before continuing with other activities.The experts say naps might improve health by reducing pressure . Some western companies have supported the idea of napping for many years. They ask people to leave work, go home and have a nap before returning. In the United States, some companies let workers rest simply in their offices. They believe this can help workers make fewer mistakes and also increase   the amount of work that a person can do. Sleep experts say it is likely that people make more mistakes at work than at other times. They say people should not carry out important tasks when they feel sleepy. And they say the best thing to do is to take a nap. About twenty minutes of rest is all you need. Experts say this provides extra energy and can increase your effects until the end of the day. But experts said that a nap should last    no more than twenty to thirty minutes. A longer nap will put the body into deep sleep and waking up will be difficult. This passage is probably taken from   _  .
a story book a poster a film review a medical magazine