영어 모의고사 (자동 편성)

Melatonin is a hormone ① produced by a small gland deep within the brain, and its release follows a remarkably predictable daily pattern. Levels stay low throughout the bright hours of the day, ② begin rising in the evening as darkness falls, peak in the middle of the night, and then decline again as morning approaches. This rhythm is controlled primarily by light: specialized cells in the eye detect brightness and send signals that either permit or ③ suppress melatonin production, which is why exposure to bright screens late at night can delay its release and make falling asleep more difficult. 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, ④ preparing various systems to shift into a lower-energy state. 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 ⑤ intending.

Insomnia is rarely caused by a single factor; it usually emerges from an interaction between psychological stress and physiological arousal that ① keeps the body from settling into sleep. A common trigger is what researchers call cognitive hyperarousal, in which the mind continues ② to racing with worries about work, relationships, or even the inability to sleep itself, creating a frustrating cycle where anxiety about insomnia becomes a cause of insomnia. At the same time, the body's stress response system can become chronically activated, ③ releasing hormones such as cortisol that keep heart rate and body temperature elevated at night, both of which interfere with the natural drop in arousal needed to fall asleep. Poor sleep habits, including irregular bedtimes and excessive screen use before bed, can further ④ weaken the body's internal signals for sleep onset. Because these psychological and physiological factors reinforce one another, effective treatment for chronic insomnia addresses both the racing mind and the underlying pattern of physical tension, rather than ⑤ relying on medication alone.

For centuries, dreams have ① fascinated scientists and philosophers alike, yet no single theory fully explains why the sleeping brain generates such vivid and often bizarre experiences. One prominent idea suggests that dreaming helps the brain process emotional experiences, replaying difficult events in a ② safe, low-stakes environment so that their emotional intensity gradually fades. Another theory proposes that dreams serve a more practical function, allowing the brain to ③ ignore responses to threats without any real danger, a kind of nightly simulation that may have offered early humans a survival advantage. 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 ④ information rather than serving any independent purpose of its own. Because these theories rest on indirect evidence, none has been ⑤ conclusively proven.

Before making a purchase, most online shoppers now read reviews written by previous customers rather than relying solely on advertisements. These reviews, posted by people who have no financial connection to the seller, often seem more ①trustworthy than promotional claims. Research shows that products with a large number of positive reviews sell significantly ②more than those with few or no reviews at all. However, fake reviews written by paid writers or even automated programs have become a serious problem, ③undermining consumer trust. Platforms that fail to detect these fraudulent posts risk ④gaining credibility with their users, who expect authentic opinions when making decisions. Ultimately, the power of online reviews depends entirely on their perceived ⑤honesty.

Across many countries, high schools begin classes ① early in the morning, often before eight o'clock. This schedule assumes that teenagers can simply go to bed earlier to compensate, but biology tells a different story. During adolescence, the body's internal clock shifts ② earlier, delaying the release of melatonin until well after ten at night. As a result, most teenagers are not physiologically ready to fall asleep until much later than younger children or adults. When early start times force them to wake before their bodies have completed a full sleep cycle, the mismatch ③ accumulates into a chronic sleep debt that affects concentration and mood throughout the school day. Researchers who study this mismatch argue that the underlying problem is not laziness or poor discipline among students, but a scheduling system built around adult rhythms rather than ④ adolescent ones. Some school districts that delayed their start times by thirty minutes reported ⑤ measurable improvements in attendance.

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 _______________.

The growing presence of AI in creative fields has sparked lively discussion among artists and critics alike. (A) In contrast, some artists worry that relying too heavily on such tools may weaken the value placed on original human creativity. (B) Many artists have embraced AI as a way to explore new styles quickly and overcome creative blocks. (C) Given these opposing views, most experts now agree that AI works best as a partner rather than a replacement for human creators.

Wearable devices that track sleep have become enormously popular, promising a detailed breakdown of light, deep, and REM sleep each night. (A) Despite these limitations, many users have come to 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. (B) Independent studies comparing 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 underestimate the amount of time spent in REM sleep, and the margin of error can vary widely between brands. (C) These gadgets typically rely on movement sensors and heart rate monitors to estimate sleep stages, since directly measuring brain activity would require equipment found only in a sleep laboratory. This indirect approach, however, introduces significant uncertainty.

When people consistently sleep too little, the body's hormonal balance shifts in ways that can quietly encourage weight gain. (A) Two hormones in particular play opposing roles in regulating appetite: leptin signals fullness to the brain, while ghrelin stimulates the sensation of hunger. (B) At the same time, insufficient sleep interferes with how efficiently the body processes glucose, making cells less responsive to insulin and leaving more sugar circulating in the bloodstream than usual. Over months or years, this combination of increased appetite and reduced insulin sensitivity can contribute to steady weight gain and raise the risk of developing type 2 diabetes. (C) Studies show that sleep deprivation lowers leptin levels while raising ghrelin levels, so a tired body ends up feeling hungrier than it actually needs to be, even after a normal-sized meal.

주어진 문장: At first, this seemed like a small, sentimental gesture with little business value. Years ago, a small shoe company struggled to compete with larger, well-funded rivals in the market. ( ① ) Its products were solid, but customers rarely remembered the brand after a single purchase. One day, the founder decided to share the story behind the company: how her grandfather had once repaired shoes for factory workers who could not afford new pairs. She began printing this story on every shoebox and posting it across social media. ( ② ) Surprisingly, customers started responding not just to the shoes themselves but to the values the story represented. ( ③ ) Sales slowly increased as people felt they were supporting something meaningful rather than simply buying a product. ( ④ ) Other companies noticed this shift and began crafting their own narratives, hoping to create similar emotional connections. ( ⑤ ) Eventually, the founder realized that a compelling story, told honestly, could turn ordinary customers into loyal supporters.