سؤال قراءة ستيب محلول — المفردات في السياق (تدريب 7093)

(1) A major effect of lessened sleep, as tired college students know, is sleepiness, and sometimes a general malaise. People today more than ever suffer from sleep patterns that prevent their having and energized feeling of well-being. Teenagers typically need 8 or 9 hours of sleep, but they now average nearly 2 hours less sleep a night than their counterparts of 80 years ago. Many fill this need by using homeroom for their siesta. (2) Some sleep-loss effects are more subtle. One such effect is suppression of the disease-fighting immune system. In rats, sleep deprivation increases the pathogens normally suppressed by the immune system. In humans, sleep deprivation suppresses immune cells that fight off viral infections. When infections do set in, immune-boosting sleep typically increases. (3) Other sleep-loss include reduced creativity and concentration, slight hand tremors, irritability, slowed performance, and occasional misperceptions on monotonous tasks. These effects can be devastating for some tasks, such as driving and piloting. Some 30 percent of Australian highway deaths occur when drivers fall asleep on long, monotonous roads. consider also the Exxon Valdez oil spill; Union Carbide’s Bhopal India disaster; and Chernobyl nuclear accidents. They all occurred after midnight, when operators were likely to be drowsiest, apparently, asleep, the Exxon Valdez captain was unresponsive to clear signals to turn his ship back into the shipping lanes. (4) On short, highly motivated tasks, however, sleep deprivation has little effect. When 17-year-old Randy Gardner made his way into the Guinness Book of World Records by staying awake for 11 days, he hallucinations and speech and movement problems. Nevertheless, during his final night of sleeplessness, Gardner managed to beat researcher Dement 100 times in a pinball game. What may suppress the immune system?