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  3. Get Enough Sleep—or Else! A good night’s sleep is more important to your health than you may realize. [A] Megan Jones knew s

Get Enough Sleep—or Else! A good night’s sleep is more important to your health than you may realize. [A] Megan Jones knew s

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问题           Get Enough Sleep—or Else!
    A good night’s sleep is more important to your health than you may realize.
[A] Megan Jones knew she was tired. Though it had been more than 24 hours since the 25-year-old Vancouverite returned from New Zealand, she was still recovering from jet lag. Jones had left New Zealand on Thursday at 7 a.m., and after a 17-hour flight she arrived in Vancouver at 7:25—Thursday morning. She forced herself to stay awake all day, hoping to force her body into sleeping through the night.
[B] But getting the sleep she needed didn’t prove easy, even though she hadn’t slept in nearly 36 hours. "I barely slept that night," Jones says. The time change had completely disrupted her sleep pattern, and she wasn’t rested when she woke at her usual 8 am.
[C] Jones wasn’t aware just how tired she was until two hours later when she set off for the grocery store—driving into the lane of oncoming traffic. "Suddenly I knew something wasn’t right," she says. "I wasn’t in New Zealand anymore. I was in Canada—driving on the wrong side of the road." Luckily she was able to pull back into the right lane without incident. "There’s no question that not getting enough sleep can lead to difficulty in concentrating, says Dr. Jeffrey Lipsitz, medical director for the Sleep Disorders Centre of Metropolitan Toronto.
[D] Whether the cause is jet lag, shift work, chronic insomnia, a sleep disorder or simply trying to put in extra hours at work, we’ve all experienced the exhaustion caused by lack of sleep. In fact, sleep is as important to a healthy lifestyle as eating properly and exercising. Studies have suggested that too little sleep may increase your risk of heart disease, stroke, diabetes, obesity and depressioa Getting a good night’s sleep is one of the simplest things you can do to stay healthy.
[E] A good night’s sleep means waking up rested and energized. On average, a healthy adult requires just over eight hours of sleep a night, according to Lipsitz.
However, the amount of sleep it takes to achieve rejuvenation varies from person to person. "It’s not a fixed number," says Joseph De Koninck, professor of psychology at the University of Ottawa, adding that if you consistently get less than you need, "a sleep deficit accumulates."
[F] The time it takes for a sleep deficit to accrue depends on how consistent the problem is, says Dr. Robert Levitan, associate professor of psychiatry at the University of Toronto. "Missing a couple of hours of sleep every night for a week is probably enough."
[G] According to studies from Wright State University in Dayton, Ohio, at least one third of adults have significant sleep loss (6.5 hours or less of sleep a night). A recent AC Nielsen poll shows that 19 percent of American adults get six hours or less a night.
[H] Why are we so sleep deprived? "We’re so busy that we often don’t allow enough time for sleep, ’’ says Dr. S.R. Dong of the Westcoast Sleep and Breathing Centre in Burnaby, B.C., who believes lifestyle is the main factor contributing to lack of sleep. According to the most recent General Social Survey done by Statistics Canada, 47 percent of Canadians will cut back on sleep in order to add time to their days.
[I] Whether it’s rushing to get the housework done once the kids have gone to bed, attending a social function or working late, we’re sleeping less than we should. The same survey reveals that 40 per-cent of Canadians report trouble sleeping when they’re severely pressed for time.
[J] For some, the problem lies not in finding the time to sleep but in their inability to fall asleep and stay that way. Sleep disorders, including insomnia (失眠症) and sleep apnea (呼吸暂停), are often the culprit Statistics Canada’s Canadian Community Health Survey says that an estimated 3.3 million Canadians over age 15 suffer from insomnia, and the U.S. National Institutes of Health reports that 70 million Americans suffer from sleep disturbances.
[K] Not sleeping enough can compromise your immune system, says Stanley Coren, author of Sleep Thieves and a professor of psychology at the University of British Columbia. You eat well and exercise in order to keep your immune system up, explains Coren, but if you aren’t sleeping, you undo all that good work. "The immune system works best when you’re asleep," he says. "That’s when your natural killer cells are generated." Natural killer cells are produced in the bone marrow and found in the blood and lymph fluid.
[L] "Natural killer cells are part of the body’s defence mechanism against viruses, bacteria, even cancer, and they do not work properly in the sleep deprived," says Dong. A study at the Cerrahpasa Medical School in Turkey found that after 24 hours of sleep deprivation, the percentage of natural killer cells in the blood declined by 37 percent. A University of California, San Diego, study of 23 males found that one night of partial sleep deprivation reduced natural-killer-cell activity to 72 percent of normal levels.
[M] Though their activity returns to normal when we begin to get proper sleep, Coren cautions that "the real problem is that a lot of damage might have been done to your body during the time that your immune system left you undefended and susceptible to infection."
[N] It’s not just your immune system that suffers when you cut down on sleep. "There is a higher rate of heart failure among people with sleep disorders and sleep disturbances," says Dr. Michael Sole, a cardiologist at the University Health Network in Toronto. According to Sole, there is increased evidence of Creactive protein, an indicator of heart disease risk, in people suffering from sleep loss.
[O] Researchers at the University of Chicago discovered that chronic sleep loss can reduce the body’s ability to regulate hormones and process carbohydrates. In their study they reduced participants’ sleep from eight to four hours a night. After less than a week, they noted changes in the body similar to the effects of early diabetes or advanced aging. "Sleep disturbances increase the likelihood of a prediabetic state and obesity," says Sole.
[P] Registered dietitian Ramona Josephson notes that insufficient sleep may affect three hormones that can contribute to obesity. There’s a decrease in leptin, the appetite-suppressing hormone found in our fat tissue, she says. Ghrelin, the hormone controlling hunger pangs, increases with lack of sleep, causing greater feelings of hunger. And our bodies produce more of the stress hormone Cortisol, which increases fat storage. Not only do the increased hormones resulting from sleep loss cause us to eat more but most of us also make poor food choices when we’re tired. "The less you sleep, the more chance you have of obesity," Josephson says.
[Q] Sleep is important in keeping not only your waistline trim, but your brain activity balanced as well, says Dr. Robert Levitan. During sleep, brain neurotransmitters—the chemicals that deliver messages between nerve cells in the brain—are replenished. "When you don’t get enough sleep, "says Levitan, "your brain chemicals become depleted and that causes emotional disturbances," including depression, anxiety, and general feelings of anger or sadness.
Lack of sleep not only affects immune system, but also increases the risk of heart disease.
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答案N
解析 题目同时提到了immune system和heart disease，结合句首的Lack of sleep可查找到N段。该段首句便提到，减少睡眠影响的不仅仅是免疫系统。接着引用Michael Sole博士的话指出睡眠不好的人发生心力衰竭的机率更高。题目句子是对该段内容的概括。
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