Sleep Deficit Judging from recent surveys, most experts in sleep behavior agree that there is virtually an epidemic(流行病)of sleepiness in the nation. “I can’t think of a single study that hasn’ t found Americans getting less sleep than they ought to, “ says Dr. David. Even people who think they are sleeping enough would probably be better off with more rest. The beginning of our sleep-deficit(睡眠不足)crisis can be traced to the invention of the light bulb a century ago. From diary entries and other personal accounts from the 18th and 19th centuries, sleep scientists have reached the conclusion that the average person used to sleep about 9.5 hours a night. “The best sleep habits once were forced on us, when we had nothing to do in the evening down on the farm, and it was dark. “By the 1950s and 1960s, that sleep schedule had been reduced dramatically, to between 7. 5 and 8 hours, and most people had to wake up to an alarm clock. “People cheat on their sleep, and they don’t even realize they’ re doing it, “says Dr. David. “They think they’ re okay because they can get by on 6. 5 hours, when they really need 7.5, 8 or even more to feel ideally vigorous. “ Perhaps the most merciless robber of sleep, researchers say, is the complexity of the day. Whenever pressures from work, family, friends and community mount, many people consider sleep the least expensive item on his programme. In our society, you’ re considered dynamic if you say you only need 5. 5 hours’ sleep. If you’ ve got to get 8. 5 hours, people think you lack drive and ambition. To determine the consequences of sleep deficit, researchers have put subjects through a set of psychological and performance tests requiring them, for instance, to add columns of numbers or recall a passage read to them only minutes earlier. “ We’ ve found that if you’ re in sleep deficit, performance suffers, “ says Dr. David. “Short-term memory is weakened, as are abilities to make decisions and to concentrate. “

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Warm People Likely to Keep Cold at Bay Staying positive through the cold season could be your best defense against getting ill, new study findings suggest. In an experiment that exposed healthy volunteers to a cold or flu virus, researchers found that people with a generally sunny disposition were less likely to fall ill. The findings, published in the journal Psychosomatic Medicine, build on evidence that a “positive emotional style “can help ward off the common cold and other illnesses. Researchers believe the reasons may be both objective as in happiness boosting immune function and subjective as in happy people being less troubled by a scratchy throat or runny nose. “ People with a positive emotional style may have different immune responses to the virus, “ explained lead study author Dr. Sheldon Cohen of Carnegie Mellon University in Pittsburgh. “And when they do get a cold, they may interpret their illness as being less severe. “ Cohen and his colleagues had found in a previous study that happier people seemed less susceptible to catching a cold, but some questions remained as to whether the emotional trait itself had the effect. For the new study, the researchers had 193 healthy adults complete standard measures of personality traits, self-perceived health and emotional “style“. Those who tended to be happy, energetic and easy-going were judged as having a positive emotional style, while those who were often unhappy, tense and hostile had a negative style. The researchers gave them nasal drops containing either a cold virus or a particular flu virus. Over the next six days, the volunteers reported on any aches, pains, sneezing or congestion they had, while the researchers collected objective data, like daily mucus production. Cohen and his colleagues found that based on objective measures of nasal woes, happy people were less likely to develop a cold.

Chest Compressions: Most Important of CPR Cardiopulmonary resuscitation, or CPR, can save the life of someone whose heart has stopped. The condition is called cardiac arrest. The heart stops pumping blood. The person stops breathing. Without lifesaving measures, the brain starts to die within four to six minutes. CPR combines breathing into the victim’ s mouth and repeated presses on the chest.【B1】______ However, a new Japanese study questions the usefulness of mouth-to-mouth breathing. The study was published in the British medical magazine, The Lancet. Doctors in Tokyo led the research. It examined more than four thousand people who had suffered cardiac arrest. In all the cases, witnesses saw the event happen. More than one thousand of the victims received some kind of medical assistance from witnesses. Seven hundred and twelve received CPR. Four hundred and thirty-nine received chest presses only.【B2】______ The researchers say any kind of CPR improved chances of the patient’ s survival. But, they said those people treated with only chest presses suffered less brain damage. Twenty-two percent survived with good brain ability.【B3】______ The American Heart Association changed its guidelines for CPR chest presses in 2005.【B4】______ Gordon Ewy is a heart doctor at the University of Arizona College of Medicine in Tucson. He wrote a report that appeared with the study. Doctor Ewy thinks the CPR guidelines should be changed again. He said the heart association should remove rescue breaths from the guidelines. He argues that more witnesses to cardiac arrests would provide treatment if rescue breaths are not a part of CPR. He says this would save lives.【B5】______ Cardiac arrest kills more than 300, 000 people in the United States every year. The American Heart Association says about ninety-five percent of victims die before they get to a medical center. A. So far, we have not known exactly yet whether mouth-to-mouth breathing is really useless in CPR. B. Only ten percent of the victims treated with traditional CPR survived with good brain ability. C. CPR keeps blood and oxygen flowing to the heart and brain. D. His studies show that many people do not want to perform mouth-to-mouth breathing on a stranger for fear of getting a disease. E. It said people should increase the number of chest presses from fifteen to thirty for every two breaths given. F. No mouth-to-mouth rescue breaths were given to them.

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Lung Cancer 1 The death rate due to cancer of the lungs has increased more than 800 percent in males and has more than doubled in females during the last 25 years. It is considerably higher in urban and industrial areas than in rural districts. There are many possible causes, but it is still controversial which are most blameworthy. Those factors which have been mentioned most frequently are the presence of foreign particles and other irritants in the air(smoke particles, smog, exhaust fumes), and the smoking of cigarettes and cigars. 2 Numerous studies have demonstrated a striking correlation between the death rate from lung cancer and smoking habits. Among heavy smokers—21 to 30 cigarettes per day—the mortality rate from lung cancer is nearly 17 times the rate from nonsmokers. It is expected the death rate among women will increase as the present high rate of smoking among women has its effect. 3 Sometimes cases of lung cancer are discovered at the time an X-ray is taken for the purpose of detecting tuberculosis. Too often, however, a current emphasis upon the danger of exposure to radiation from X-ray machines can frighten people away from routine chest X-rays and thus prevent an early diagnosis of lung cancer. Early detection is absolutely essential if any possibility of cure is to be maintained. Modern X-ray machines in competent hands pose such slight danger, at least to those over 40 years of age, that this would be much more than offset by the advantages of discovering a tumor while it is small enough to be completely removed. 4 A common form of lung cancer is bronchogenic carcinoma, so-called because the malignancy originates in a bronchus. The tumor may grow until the bronchus is blocked, cutting off the supply of air to that lung. The lung then collapses, and the secretions trapped in the lung spaces become infected, with a resulting pneumonia or the formation of a lung abscess. Such a lung cancer can also spread to cause secondary growths in the lymph nodes of the chest and neck as well as in the brain and other parts of the body. The only treatment that offers a possibility of cure, before secondary growths have had time to form, is to remove the lung completely. This operation is called pneumonectomy. 5 Malignant tumors of the stomach, the breast, the prostate gland and other organs may spread to the lungs, causing secondary growths. A. Common Secondary Lung Cancers B. The Advantages Brought About by Routine Chest Checkup C. Relationship Between Mortality Rate From Lung Cancer and Smoking Habits D. Operable and Inoperable Lung Cancers E. The Increasing Death Rate From Lung Cancer and Possible Causes F. An Ordinary Type of Lung Cancer

A. before the cancer cells spread elsewhere B. the more chances of dying of X-ray radiation he will have C. what is most responsible for lung cancer D. as some people imagine E. the more chances of getting lung cancer he will have F. which form of lung cancer is a common one

Most Adults in US Have Low Risk of Heart Disease More than 80 percent of US adults have a less than 10-percent risk of developing heart disease in the next 10 years, according to a report in the Journal of the American College of Cardiology. Just 3 percent have a risk that exceeds 20 percent. “ I hope that these numbers will give physicians, researchers, health policy analysts, and others a better idea of how coronary heart disease is distributed in the US population, “ lead author Dr. Earl S. Ford, from the Centers for Disease Control and Prevention in Atlanta, said in a statement. The findings are based on analysis of data from 13, 769 subjects, between 20 and 79 years of age, who participated in the Third National Health and Nutrition Examination Survey from 1988 to 1994. Overall, 82 percent of adults had a risk of less than 10 percent, 15 percent had a risk that fell between 10 to 20 percent, and 3 percent had a risk above 20 percent. The proportion of subjects in the highest risk group increased with advancing age, and men were more likely than women to be in this group. By contrast, race or ethnicity had little effect on risk distributions. Although the report suggests that most adults have a low 10-year risk of heart disease, a large proportion have a high or immediate risk, Dr. Daniel S. Berman, from Cedars-Sinai Medical Center in Los Angeles, and Dr. Nathan D. Wong, from the University of California at Irvine, note in a related editorial. Aggressive treatment measures and public health strategies are needed to shift the overall population risk downward, they add.

Prolonging Human Life Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion. Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of famine, infants might be allowed to die because they could not survive if their parents starved, whereas if the parents survived they could have another child. In most contemporary societies, people feel a moral obligation to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work; we also have rules which require people to retire at a certain age. Unless these people were able to save money for their retirement, somebody else must support them. In the United States many retired people live on social security checks which are so little that they must live in near poverty. Older people have more illness than young or middle-aged people; unless they have wealth or private or government insurance, they must often “go on welfare“ if they have a serious illness. When older people become senile or too weak and ill to care for themselves, they create grave problems for their families. In the past and in some traditional cultures, they would be cared for at home until they died. Today, with most members of a household working or in school, there is often no one at home who can care for a sick or weak person. To meet this need, a great many nursing homes and convalescent hospitals have been built. These are often profit-making organizations, although some are sponsored by religious and other nonprofit groups. While a few of these institutions are good, most of them are simply “ dumping grounds“ for the dying in which “care“ is given by poorly paid, overworked, and underskilled personnel.

People in the 18th and 19th centuries used to sleep about 9.5 hours a night because they had______.

According to Dr. David, Americans______.

Many Americans believe that______.

The word “subjects“(Line 1 , Para 4)refers to______.

It can be inferred from this passage that one should sleep as many hours as is necessary to