영어 모의고사 (자동 편성)

Travelers who cross several time zones in a single flight often arrive ①feeling exhausted, foggy, and strangely out of sync with the local clock. The discomfort arises because the body's internal clock, ②which governs sleep, hunger, and alertness, continues to run on the schedule of the departure city even after landing. Realigning this internal clock to a new time zone is not instantaneous; researchers estimate that the body typically needs about one day ③to adjust for every time zone crossed. Flying eastward tends to produce more severe symptoms than flying westward, because advancing the internal clock forward ④are generally harder for the body than delaying it. Exposure to natural light at the right moments after arrival can help speed up the adjustment, since light is the strongest external cue the internal clock ⑤uses to reset itself.

Elite athletes often perform in front of enormous crowds with championships, contracts, and years of training riding on a single moment, and the psychological weight of that pressure can ①undermine skills that feel automatic in practice. Sports psychologists explain that intense anxiety narrows attention and disrupts the smooth, unconscious execution of well-learned movements, a phenomenon sometimes ②called choking under pressure. Rather than trying to eliminate nervousness entirely, which research suggests ③are nearly impossible, many trainers now teach athletes ④to reinterpret the physical symptoms of anxiety, such as a racing heart, as signs of readiness rather than danger. Over time, repeated exposure to high-pressure situations in practice, deliberately ⑤simulated to resemble real competition, allows athletes to build tolerance the same way their muscles adapt to physical training.

Wearable devices ①that track sleep have become enormously popular, promising a detailed breakdown of light, deep, and REM sleep each night. These gadgets typically rely on movement sensors and heart rate monitors ②to estimate sleep stages, since directly measuring brain activity would require equipment found only in a sleep laboratory. Independent studies ③compares wearable data with polysomnography, the gold-standard method used in clinical sleep labs, have found that consumer devices are reasonably accurate at distinguishing sleep from wakefulness but considerably less reliable at identifying specific sleep stages. Some trackers overestimate deep sleep, while others ④underestimate the amount of time spent in REM sleep, and the margin of error can vary widely between brands. Despite these limitations, many users have come ⑤to treat the nightly score generated by their device as an objective medical verdict, sometimes experiencing anxiety when the number falls below what they expect, a phenomenon researchers have begun calling orthosomnia.

For centuries, dreams have fascinated scientists and philosophers alike, yet no single theory fully ①explains why the sleeping brain generates such vivid and often bizarre experiences. One prominent idea suggests that dreaming helps the brain process emotional experiences, ②replays difficult events in a safe, low-stakes environment so that their emotional intensity gradually fades. Another theory proposes that dreams serve a more practical function, ③allowing the brain to rehearse responses to threats without any real danger. Still other researchers argue that dreaming is simply a byproduct of the brain organizing memories, with vivid imagery ④arising as the mind sorts through the day's information rather than serving any independent purpose of its own. Because these theories rest on indirect evidence, none has ⑤been conclusively proven.

Ambitious young athletes and the parents who support them sometimes ①assumes that more training automatically produces better results, a belief that occasionally leads to a condition known as overtraining syndrome. Unlike ordinary fatigue that resolves after a few days of rest, overtraining syndrome develops gradually over weeks or months of insufficient recovery relative to training load, eventually ②producing persistent exhaustion, declining performance despite continued hard work, and increased susceptibility to illness and injury. Adolescents may be especially vulnerable, since their bodies are simultaneously ③coping with the physical demands of growth and the added stress of intensive training schedules. Warning signs are often subtle at first, including disrupted sleep, irritability, and a loss of enthusiasm for a sport the athlete once genuinely enjoyed, which adults often ④mistake for ordinary moodiness. Recovery from full-blown overtraining syndrome can take months rather than days, which is why sports medicine specialists now emphasize ⑤monitoring early warning signs and scheduling rest before symptoms worsen.

Across the world, teenagers are chronically short on sleep, often getting two or three hours less than the eight to ten hours experts recommend for their age. Part of the problem lies in biology: as puberty begins, the body's internal clock naturally ①shifts later, making it difficult for teenagers to fall asleep before eleven at night. Yet school start times rarely adjust to this shift, forcing students to wake before their bodies are ready. The consequences extend well beyond simple tiredness. Chronic sleep loss during adolescence has been linked to ②impaired concentration, weakened memory, and a higher risk of anxiety and depression. It can also disrupt the hormones that regulate appetite, contributing to ③unhealthy weight gain over time. Some school districts have experimented with delaying start times by even thirty minutes, and early results suggest that students who gain that extra rest show ④worsened grades, better mood, and fewer tardy arrivals. Despite this evidence, changing entrenched school schedules remains a slow and ⑤contentious process.

During sleep, the brain does not simply rest; it actively reorganizes the day's experiences into lasting memories through a process called consolidation. Newly formed memories are initially fragile and stored primarily in a brain region called the hippocampus, which has limited long-term capacity. While a person sleeps, particularly during the deep stages of non-REM sleep, neural activity replays these fresh memory traces in rapid, compressed sequences, gradually transferring the information to the cortex for more durable, long-term storage. This replay strengthens the connections between neurons that encoded the original experience, making the memory more resistant to interference from unrelated events the following day. Sleep researchers have demonstrated this effect experimentally: participants who slept after learning a list of word pairs recalled more items the next day than participants who remained awake instead. Crucially, the benefit was not limited to simple recall; sleep also seemed to help participants extract general patterns from the material, suggesting that _______________.

Habit researchers often note that people overestimate the role of motivation in daily routines. (A) As a result, they frequently give up soon after starting, blaming themselves for lacking discipline. (B) In contrast, Fogg's framework suggests that shrinking the task itself is more effective than boosting motivation. (C) Because motivation naturally rises and falls, relying on it alone often leads to inconsistent effort.

Sleep debt refers to the cumulative gap between the amount of sleep a person needs and the amount they actually get. (A) Unlike a financial debt, however, this deficit cannot simply be repaid with a single long weekend of rest. (B) When someone loses two hours of sleep every night for a week, the body does not treat the shortage as fourteen separate small losses; instead, it accumulates the deficit, and the resulting impairment in attention and mood can resemble that of a person who has been awake for an entire night. (C) Researchers have found that even modest, chronic sleep restriction gradually impairs reaction time and decision-making, often without the affected person noticing the decline. This is because subjective feelings of tiredness tend to plateau after a few days, even as objective performance keeps deteriorating. Consequently, people frequently underestimate how much sleep debt they are carrying until a demanding task suddenly exposes the accumulated cost.

This happens because the eyes remain remarkably responsive to light even after darkness falls, cueing the brain that it is still daytime. Smartphones, tablets, and computer screens all emit a significant amount of blue light, a short-wavelength light that our eyes are especially sensitive to. ( ① ) During the day, exposure to blue light from the sun helps keep us alert and mentally sharp, which is generally beneficial. ( ② ) At night, however, the same wavelength can interfere with the body's natural preparation for sleep. ( ③ ) Specialized cells in the retina detect blue light and send signals to the brain's internal clock, suppressing the release of melatonin, the hormone that signals it is time to rest. ( ④ ) Studies have found that people who scroll through their phones in bed before sleeping take longer to fall asleep and experience lighter, more easily disrupted sleep than those who avoid screens. ( ⑤ ) Some devices now offer a night mode that shifts the display toward warmer tones, reducing blue light output in the evening. While this feature may help slightly, sleep researchers generally recommend limiting screen use altogether in the hour before bedtime for the best results.