영어 모의고사 (자동 편성)

Sleep debt refers to the cumulative gap between the amount of sleep a person needs and the amount they actually get. Unlike a financial debt, however, this deficit cannot simply ①be repaid with a single long weekend of rest. 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 ②who has been awake for an entire night. Researchers have found that even modest, chronic sleep restriction gradually impairs reaction time and decision-making, often without the affected person ③noticing the decline. This is because subjective feelings of tiredness tend to plateau after a few days, even as objective performance keeps ④deteriorate. Consequently, people frequently underestimate how much sleep debt they are carrying until a demanding task suddenly ⑤exposes the accumulated cost.

Skipping a proper warm-up before intense exercise might seem like a harmless way to save a few minutes, but the practice carries real physiological costs. A cold muscle is ①more flexible and less elastic than a warm one, making it considerably more prone to strains and tears when suddenly asked to contract forcefully. Gradually raising body temperature through light activity ②increases blood flow to the muscles, allowing oxygen to reach tissue more efficiently and enabling nerve signals to travel faster between the brain and the muscle fibers. A proper warm-up also raises heart rate gradually, ③easing the cardiovascular system into strenuous work rather than shocking it with a sudden demand. Athletes who warm up thoroughly tend to report ④better performance in the early minutes of competition, since their bodies are already ⑤primed rather than adjusting on the fly.

Researchers who study teenagers have found a ①strong link between how well students sleep and how well they perform in school. Students who sleep fewer than seven hours a night tend to score ②lower on tests of memory and attention than those who sleep eight or nine hours, even when the two groups study for the same number of hours. One explanation is that sleep plays an active role in learning: during certain stages of sleep, the brain replays and strengthens information encountered during the day, converting fragile short-term memories into more ③durable long-term ones. When sleep is cut short, this consolidation process is interrupted before it can finish, so material that seemed well understood the night before often feels ④unfamiliar the next morning. For this reason, some schools have begun ⑤confirming early start times, reasoning that an extra hour of sleep might do more for test scores than an extra hour of studying ever could.

Sleep apnea is a disorder in which breathing repeatedly stops and restarts during sleep, often because the muscles at the back of the throat ①relax too much and block the airway. Each pause can last from a few seconds to over a minute, and it may occur dozens of times in a single night without the sleeper ever ②waking up fully. Because these interruptions rarely produce a clear memory the next morning, many people remain ③unaware that anything is wrong, even as chronic fatigue, headaches, and irritability build up over months. Doctors therefore rely less on a patient's own account of the night and more on ④subjective measurements, such as overnight oxygen levels and airflow patterns recorded in a sleep laboratory. Left untreated, the disorder has been linked to serious long-term risks, including high blood pressure and heart disease, which makes an accurate diagnosis far more ⑤urgent than its subtle nighttime symptoms might suggest.

Browsing an online store today often means chatting with an AI assistant that asks a few quick questions before suggesting a short list of products tailored to the answers. Retailers report that shoppers who use these chatbots tend to complete purchases more often and return fewer items, since the guided conversation helps buyers choose products that actually fit their needs. Some shoppers, however, remain wary of how personal the questions can feel, wondering _______________. Consumer advocates argue that stores should clearly explain what happens to this data, rather than burying the explanation in a lengthy privacy policy that almost no one reads.

When the body fights off an infection, the immune system relies heavily on adequate sleep to function effectively. During deep sleep, the body produces and releases cytokines, proteins that help regulate immune responses and coordinate the fight against harmful invaders. People who consistently sleep fewer than six hours a night show measurably weaker antibody responses after vaccination compared with those who sleep seven or eight hours, suggesting that _______________. Chronic sleep deprivation also appears to promote low-grade inflammation throughout the body, a state that has been linked to a higher risk of heart disease. Rather than being a passive state, sleep functions as an active period during which the immune system repairs itself and prepares for future threats.

After a viewer finishes an episode, a streaming service rarely leaves the choice of what to watch next entirely up to chance. (A) The system is not without drawbacks, however, since favoring titles similar to what a viewer already enjoys can quietly narrow someone's exposure to unfamiliar genres, directors, or cultures. (B) Instead, a recommendation algorithm compares that viewer's habits with patterns drawn from millions of other users, then ranks thousands of titles in order of predicted interest. (C) This approach keeps viewers engaged far longer than a simple list of new releases ever could, which is precisely why streaming companies invest so heavily in refining it.

None of these explanations, in other words, has to be the whole story. For centuries, dreams have fascinated scientists and philosophers alike, yet no single theory fully explains why the sleeping brain generates such vivid and often bizarre experiences. ( ① ) One prominent idea suggests that dreaming helps the brain process emotional experiences, replaying difficult events in a safe, low-stakes environment so that their emotional intensity gradually fades. ( ② ) Another theory proposes that dreams serve a more practical function, allowing the brain to rehearse responses to threats without any real danger, a kind of nightly simulation that may have offered early humans a survival advantage. ( ③ ) Still other researchers argue that dreaming is simply a byproduct of the brain organizing memories, with vivid imagery arising as the mind sorts through the day's information rather than serving any independent purpose of its own. ( ④ ) Because these theories rest on indirect evidence rather than direct observation of subjective experience, none has been conclusively proven. ( ⑤ ) Many scientists now suspect that dreaming may serve several of these functions simultaneously rather than just one.

주어진 문장: This heightened sensitivity can manifest in a variety of noticeable ways. In recent years, mental health experts have identified a distinct emotional response to environmental crisis, commonly called eco-anxiety. ( ① ) Eco-anxiety describes persistent worry, grief, or fear triggered by awareness of climate change and its consequences for the future. ( ② ) Although people of all ages can experience it, teenagers and young adults seem especially vulnerable, since they anticipate living through decades of worsening conditions. ( ③ ) Common symptoms include difficulty sleeping, a sense of hopelessness, and guilt over ordinary choices such as travel or diet. ( ④ ) For example, some students report feeling paralyzed whenever they read alarming climate news, unable to focus on schoolwork or hobbies. ( ⑤ ) However, experts emphasize that eco-anxiety is not a disorder to be eliminated but a natural reaction that can be channeled productively. Rather than avoiding the topic, young people are encouraged to join community projects, since taking constructive action tends to restore a sense of control and ease overwhelming distress.

Because this feedback loop relies entirely on light rather than on the clock on the wall, melatonin release can shift dramatically when a person travels across time zones or works through the night. Melatonin is a hormone produced by a small gland deep within the brain, and its release follows a remarkably predictable daily pattern. ( ① ) Levels stay low throughout the bright hours of the day, begin rising in the evening as darkness falls, peak in the middle of the night, and then decline again as morning approaches. ( ② ) This rhythm is controlled primarily by light: specialized cells in the eye detect brightness and send signals that either permit or suppress melatonin production, which is why exposure to bright screens late at night can delay its release and make falling asleep more difficult. ( ③ ) Unlike some hormones that directly cause the body to perform a task, melatonin does not force sleep to occur; instead, it signals to the rest of the body that night has arrived, preparing various systems to shift into a lower-energy state. ( ④ ) Because of this signaling role, taking melatonin supplements at the wrong time can shift a person's internal clock in the opposite direction from what was intended. ( ⑤ )