Sleep

Paragraph 1: Why do we sleep? It can be dangerous to lose awareness of the external world. If nothing else, sleep might seem to take away from time that could be spent on productive, or even necessary, activities. But people cannot override indefinitely the desire to sleep; the body shuts down whether we like it or not. There are three general explanations that describe the adaptiveness of sleep: restoration, circadian cycles, and facilitation of learning. 

 

 

Paragraph 2: The restoration theory of sleep emphasizes that the brain and body need to rest and that sleep allows the body to repair itself. Indeed, growth hormone’s released during deep sleep, and one of its functions is to facilitate repair of damaged tissue. Additional evidence that sleep is a time of restoration is that people who have engaged in vigorous physical activity, such as running marathons, seem to sleep longer. But people sleep even if they spend the day being physically inactive. In addition, it appears that sleep allows the brain to strengthen the body’s ability to fight disease. 

 

 

 

1. According to paragraph 2, all of the following are considered to be evidence that sleep is needed for the body to repair itself EXCEPT: 

 

A. The body’s resistance to disease is strengthened through sleep. 

 

B. Body tissues are restored by the release of hormones during sleep. 

 

C. The longer people sleep, the more activity occurs. 

 

D. Sleep occurs whether or not physical activity has taken place.

 

 

 

 

 

Paragraph 3: Numerous laboratory studies have examined the effects of sleep deprivation on physical and cognitive performance. Surprisingly, most studies find that two or three days of deprivation have little effect on strength, athletic ability, or cognitive performance on complex tasks. Performing boring or ordinary tasks when sleep deprived, however, is nearly impossible. A brain-imaging study of sleep-deprived people found increased activation of the prefrontal cortex, suggesting that some brain regions may compensate for the effects of deprivation. Over long periods, however, sleep deprivation eventually causes problems with mood and cognitive performance. Indeed, studies using rats have found that extended sleep deprivation compromises the immune system and leads to death. Interestingly, sleep deprivation might serve one very useful purpose, which is helping people overcome depression. Consistent evidence has emerged over the past decade demonstrating that depriving depressed people of sleep sometimes alleviates their depression. This effect appears to occur because sleep deprivation leads to increased activation of serotonin receptors, which combat depression. 

 

 

 

2. Why does the author say “Performing boring or ordinary tasks when sleep deprived, however, is nearly impossible”? 

 

A. To identify a type of task in which being sleep-deprived for a few days actually does affect physical and cognitive performance

 

B. To suggest that simple tasks are easier to perform than complex tasks after sleep deprivation 

 

C. To indicate an important finding of a brain-imaging study on the effects of sleep deprivation on the prefrontal cortex 

 

D. To suggest that physical acts are preformed more easily than cognitive acts after sleep deprivation 

 

 

3. According to paragraph 3, what was one unexpected finding reported by studies investigating sleep deprivation? 

 

A. Sleep deprivation helps people perform better on complex tasks. 

 

B. Sleep deprivation of a few days’ duration does not significantly weaken performance on challenging tasks.

 

C. Sleep deprivation is more common in people who are physically inactive than it is in active people. 

 

D. Sleep deprivation can sometimes temporarily improve physical abilty. 

 

 

 

4. Which of the following can be inferred from the discussion about sleep deprivation in paragraph 3？ 

 

A. Short-term sleep deprivation has a negative impact on athletic performance. 

 

B. Short-term sleep deprivation severely harms the immune system. 

 

C. Sleep deprivation can have both positive and negative effects.

 

D. Sleep deprivation improves cognitive development by activating serotonin receptors. 

 

 

 

 

 

Paragraph 4: The circadian rhythm theory of sleep proposes that sleep has evolved to keep animals quiet and inactive during times of the day when there is greatest danger, which for most is when it is dark. Physiological and brain processes are regulated into regular patterns known as circadian rhythms (“circadian” roughly translates to “about a day”). Body temperature, hormone levels, and sleep-wake cycles are all examples of circadian rhythms, which operate like biological clocks. These circadian rhythms are themselves controlled by cycles of light and dark, although animals continue to show these rhythms when light cues are removed. 

 

 

 

5. According to paragraph 4, which of the following is NOT true of the circadian rhythms of animals? 

 

A. Circadian rhythms regulate physiological processes such as body temperature, hormone levels, and sleep-wake cycles of animals. 

 

B. Animals that are kept in darkness will stop following circadian rhythms.

 

C. The daily periods of light and dark regulate the circadian rhythms of animals. 

 

D. Sleep occurs during the part of the circadian cycle in which an active animal would be in the most danger. 

 

 

 

 

 

Paragraph 5: According to the circadian rhythm theory, animals need only so much time in the day to accomplish the necessities of survival, and it is adaptive to spend the remainder of the time inactive, preferably hidden away. Accordingly, the amount an animal sleeps depends on how much time it needs to obtain food, how easily it can hide, and how vulnerable it is to attack. Small animals sleep a great deal, whereas large animals vulnerable to attack, such as cows and deer, sleep little. Large animals that are not vulnerable, such as lions, also sleep a great deal. 

 

 

 

6. According to the circadian rhythm theory described in paragraph 5, which of the following does NOT determine the amount of time an animal sleeps? 

 

A. How easily the animal can hide from attackers 

 

B. How much energy the animal’s food provides

 

C. How likely it is that the animal will be attacked when it is active 

 

D. The amount of time the animal needs to find food 

 

 

 

 

 

Paragraph 6: It has been proposed that sleep may be important because it is involved in the strengthening of nerve cell connections that serve as the basis of learning. The general idea is that circuits that have been wired together during the waking period are consolidated, or strengthened, during sleep. Robert Stickgold and colleagues conducted a study in which they required participants to learn a complex visual-discrimination task. They found that participants improved at the task only if they had slept for at least six hours following training. Periods of sleep with increased brain activity as well as periods of sleep with reduced brain activity appeared to be important for learning to take place. The researchers argued that learning the task required nerve cell changes that normally occur only during sleep. Although learning certainly can take place in the absence of sleep, sleep seems to be an efficient time for the consolidation of learning. Infants and the very young, who learn an incredible amount in a few short years, sleep the most and also spend the most time in periods of sleep with higher brain activity. 

 

 

 

7. According to paragraph 6, what was a major finding of the study conducted by Robert Stickgold and his colleagues? 

 

A. Most learning takes place during deep sleep. 

 

B. Information and skills acquired during the day are reinforced during sleep.

 

C. Visual discrimination tasks cannot be learned without sleeping afterward. 

 

D. At least six hours of sleep before performing a task is necessary for learning to occur. 

 

 

 

8. In paragraph 6, why does the author mention that infants and very young people sleep the most? 

 

A. To argue against the findings of the study conducted by Robert Stickgold and his colleagues 

 

B. To suggest that learning is not possible if infants and young people are deprived of sleep 

 

C. To support the claim that sleep is critical to learning and reinforces it in important ways

 

D. To indicate that the brain circuits responsible for learning are more active in infants and young people than they are in adults 

 

 

 

 

 

Paragraph 4: The circadian rhythm theory of sleep proposes that sleep has evolved to keep animals quiet and inactive during times of the day when there is greatest danger, which for most is when itis dark. Physiological and brain processes are regulated into regular patterns known as circadian rhythms (“circadian” roughly translates to “about a day”). Body temperature, hormone levels, and sleep-wake cycles are all examples of circadian rhythms, which operate like biological clocks. ■These circadian rhythms are themselves controlled by cycles of light and dark, although animals continue to show these rhythms when light cues are removed. 

 

 

 

Paragraph 5: ■According to the circadian rhythm theory, animals need only so much time in the day to accomplish the necessities of survival, and it is adaptive to spend the remainder of the time inactive, preferably hidden away. ■Accordingly, the amount an animal sleeps depends on how much time it needs to obtain food, how easily it can hide, and how vulnerable it is to attack. Small animals sleep a great deal, whereas large animals vulnerable to attack, such as cows and deer, sleep little. ■Large animals that are not vulnerable, such as lions, also sleep a great deal. 

 

 

 

9. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? 

 

But how do biological clocks affect the amount of time an animal sleeps each day?

 

 

 

 

 

10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selected THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. 

 

Several theories have been proposed to explain why sleep is important. 

 

 

 

Answer Choices 

 

A. Sleep may be necessary to increase the body’s energy for use in physical activity, which in turn may speed up the process of tissue restoration. 

 

B. Sleep may help repair damage to the body, although evidence suggests that only a long-term lack of sleep would cause a decline in physical health and cognitive functioning. 

 

C. Sleep may control the development of daily rhythms that regulate basic physiological properties, such as body temperatures and hormone levels. 

 

D. The function of sleep cycles in animals may be to allow them to minimize activity during periods of high risk. 

 

E. Sleep may influence brain development by increasing the number of neuronal connections, which would explain why infants demonstrate higher brain activity than adults do. 

 

F. Sleep may enable certain physiological changes that normally occur only during sleep to support and strengthen the process of learning. 

 

 

 

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