THE EFFECTS OF SLEEP DEPRIVATION
1 Sleep restores the body and the mind and helps prevent disease by strengthening the immune system. However, many adults do not get the recommended eight hours of sleep each night. The average adult today gets only 6.4 hours of sleep, nearly an hour and a half less than what the average person received a century ago. Only in recent years have health professionals begun to realize the prevalence and severity of sleep deprivation in the working population. A significant number of people work at night, work long shifts, or suffer from insomnia or jet lag. Others are deprived of sleep because they work too hard, stay out too late, or try to do too many things in a day. Adults who regularly sleep six hours or less might think they accomplish more by staying up late, but they pay for it the next day when they feel sleepy or irritable or are unable to concentrate, remember things, or be very effective at their work.
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2 Studies show that the brain is adversely affected by sleep deprivation because certain patterns of electrical and chemical activity that occur during sleep are interrupted and the brain cannot function normally. In one study, thirteen healthy adult subjects who usually had normal sleep patterns were kept awake and carefully monitored in a hospital sleep laboratory during a period of 35 hours. During the experiment, the subjects were asked to perform several cognitive tasks, such as arithmetic and word problems, while undergoing magnetic resonance scans of their brain activity. The scans recorded each subject’s brain activity from a rested state through various stages of sleep deprivation over the 35-hour period. The scans produced images showing increased activity in some regions of the brain and decreased activity in others. The researchers found that the temporal lobe of the brain, the region involved in language processing, was activated during verbal tasks in rested subjects but not in sleep-deprived subjects. When subjects were fully rested their magnetic resonance scans showed that the temporal lobe was very active. However, after several hours without sleep, there was no activity within this region, The effects of the inactivity included slurred speech in the subjects who had gone for prolonged periods with no sleep.
3 Several studies show that getting fewer than six hours of sleep a night can impair short-term memory, coordination, reaction time, and judgment—thus posing a serious risk of accident or injury. In one study of drivers, researchers reported that sleep deprivation had some of the same hazardous effects as being drunk. They found that people who drove after being awake for 17 to 19 hours performed worse than those with a blood alcohol level of .05 percent, the legal limit for drunk driving in most western European countries. The study also found that 16 to 60 percent of road accidents involved sleep deprivation. The researchers concluded that countries with drunk driving laws should consider similar restrictions against sleep-deprived driving.
4 There are other problems associated with sleep deprivation beyond impaired motor skills and judgment. Drivers who get too little sleep may have higher levels of stress, anxiety and depression, may take unnecessary risks, or may express rage toward other drivers. These dangers affect not only drivers but also people who work long shifts or night shifts, such as medical personnel and other emergency workers. The dangers of sleep deprivation go far beyond the obvious risks and can, in fact, undermine all areas of an individual’s physical and mental health.
5 Sleep deprivation weakens the immune system, making an individual more prone to diseases such as the common cold and diabetes. Without sleep, the number of disease-fighting white blood cells within the body decreases, as does the activity of the remaining white blood cells. Sleep deprivation has been linked to a decrease in the body’s production of hormones such as insulin. Results of a recent study suggested that healthy young adults who regularly got under 6.5 hours of sleep a night had greater insulin resistance than people who got 7,5 to 8.5 hours of sleep. Insulin resistance is a silent condition in which the pancreas does not make enough insulin or the body is unable to use the insulin that is present. Thus, the muscle and liver cells cannot metabolize the sugar called glucose. As a result, glucose builds up in the bloodstream, setting the stage for diabetes and heart disease.
insomnia: the inability to fall asleep or remain asleep
jet lag: the disruption of bodily rhythms caused by high-speed travel across time zones cognitive: relating to mental processes
27. Which sentence below best expresses the essential information in the highlighted sentence in paragraph 1 ? Incorrect choices change the meaning in important ways or leave out essential information.
(A) A century ago, health professionals did not experience sleep deprivation; however, now it is a part of their jobs.
(B) It is difficult to understand why health professionals have not studied the consequences of sleep deprivation.
(C) Sleep deprivation used to affect only certain professions, but now it occurs in all sectors of the working population.
(D) Health professionals have just started to understand that sleep deprivation in workers is a serious problem,
28. The passage mentions all of the following as causes of sleep deprivation EXCEPT
(A) jet lag
(B) long work hours
(C) boring work
(D) working at night
29. The phrase deprived of in paragraph 1 is closest in meaning to
(A) disgusted by
(B) capable of
(D) worried about
30. The word adversely in paragraph 2 is closest in meaning to
31. The purpose of the study described in paragraph 2 was to determine
(?) how many hours people can survive without sleep
(?) how people react when their sleep is interrupted
(?) the changes in brain activity that occur during sleep
(?) the effects of sleep deprivation on brain activity
32. The word others in paragraph 2 refers to
(?) magnetic resonance scans
(?) stages of sleep deprivation
(?) regions of the brain
(?) rested subjects
33. According to paragraph 2, what did researchers learn about subjects who had gone several hours without sleep?
(?) The subjects were unable to complete simple word problems.
(?) The subjects had no activity in part of the brain during verbal tasks.
(?) The subjects could solve some cognitive tasks better than others.
(?) The subjects felt irritable and expressed anger in their speech.
34. Why does the author mention blood alcohol level in paragraph 3?
(?) To show how sleep deprivation reduces the blood alcohol level
(?) To compare the effects of sleep deprivation and alcohol
(?) To suggest that sleep-deprived drivers are also likely to drink
(?) To argue against raising the legal limit for drunk driving
35. It can be inferred from paragraph 4 that medical personnel and other emergency workers
(A) are at risk for experiencing anxiety and depression
(B) are more likely than drivers to be deprived of sleep
(C) are not aware that they may suffer from sleep deprivation
(D) are rarely able to find jobs with daytime hours
36. According to the passage, sleep deprivation can affect the body’s immune system by
(A) increasing the number of white blood cells
(B) decreasing the body’s resistance to insulin
(C) reducing the body’s ability to make or use insulin
(D) raising the heart rate and blood pressure
37. The phrase setting the stage in paragraph 5 is closest in meaning to
(A) lowering the risk
(B) changing the treatments
(C) eliminating the cure
(D) providing the conditions
38. Look at the four squares, [A], [B], [C], [D] which indicate where the following sentence could be added to the passage. Where would the sentence best fit?
Drivers are especially at risk, and fatigue caused by sleep deprivation causes thousands of traffic accidents every year.
[A] Several studies show that getting less than six hours of sleep a night can impair short¬term memory, coordination, reaction time, and judgment—thus posing a serious risk of accident or injury, [B] In one study of drivers, researchers reported that sleep deprivation had some of the same hazardous effects as being drunk. [C] They found that people who drove after being awake for 17 to 19 hours performed worse than those with a blood alcohol level of .05 percent, the legal limit for drunk driving in most western European countries. The study also found that 16 to 60 percent of road accidents involved sleep deprivation. The researchers concluded that countries with drunk driving laws should consider similar restrictions against sleep-deprived driving. [D]
39. Read the first sentence of a summary of the passage. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Sleep deprivation affects the human body in numerous ways.
(A) The average adult gets only 6.4 hours of sleep a night, which is less than the recommended eight hours.
(B) Illness, depression, pain and discomfort at night, and significant life stress are common causes of insomnia.
(C) Lack of sleep disrupts normal activity in parts of the brain, affecting one’s ability to perform certain tasks.
(D) Subjects in one study were deprived of sleep for 35 hours, and their brain activity was scanned by magnetic resonance.
(E) Sleep deprivation can have effects similar to being drunk, such as impairment of motor skills and judgment.
(F) Not getting enough sleep can weaken the immune system and harm a person’s physical and mental health.