영어 모의고사 (자동 편성)

Travelers who cross several time zones in a single flight often arrive feeling ① exhausted, foggy, and strangely out of sync with the local clock. The discomfort arises because the body's internal clock, which governs sleep, hunger, and alertness, continues to run on the schedule of the departure city even after landing. ② Realigning this internal clock to a new time zone is not instantaneous; researchers estimate that the body typically needs about one day to adjust for every time zone crossed. Flying eastward tends to produce more ③ severe symptoms than flying westward, because advancing the internal clock forward is generally harder for the body than delaying it. Exposure to natural light at the right moments after arrival can help ④ speed up the adjustment, since light is the strongest external cue the internal clock uses to reset itself. Without such adjustments, travelers may continue to experience disrupted sleep and reduced concentration for ⑤ several minutes after a long international flight.

Social media researchers use the term context collapse to describe what happens when a single online post reaches audiences that would normally remain ①separate in offline life. In daily interactions, people naturally adjust their tone and content depending on whether they are speaking with family, close friends, or professional colleagues. However, a typical social media feed ②merges these distinct audiences into one undivided crowd, since a single post can simultaneously reach parents, employers, and casual acquaintances. Consequently, users often struggle to decide which version of themselves to present, knowing that a joke suitable for close friends might seem ③professional to a supervisor. This tension forces many users to either ④self-censor heavily or maintain multiple separate accounts tailored to different audiences. Understanding context collapse helps explain why online communication often feels more ⑤complicated.

When people consistently sleep too little, the body's hormonal balance shifts in ways that can ① quietly encourage weight gain. Two hormones in particular play ② opposing roles in regulating appetite: leptin signals fullness to the brain, while ghrelin stimulates the sensation of hunger. Studies show that sleep deprivation lowers leptin levels while raising ghrelin levels, so a tired body ends up feeling ③ fuller than it actually needs to be, even after a normal-sized meal. At the same time, insufficient sleep interferes with how efficiently the body processes glucose, making cells less ④ 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. Because these effects build up so ⑤ gradually, many people never connect their shifting eating habits or worsening blood sugar to something as ordinary as a few lost hours of sleep each night.

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, _______________. 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 impaired concentration, weakened memory, and a higher risk of anxiety and depression. It can also disrupt the hormones that regulate appetite, contributing to unhealthy 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 improved grades, better mood, and fewer tardy arrivals. Despite this evidence, changing entrenched school schedules remains a slow and contentious process.

Caffeine is the most widely consumed stimulant in the world, prized for its ability to sharpen focus and fight off fatigue within minutes of consumption. It works by blocking adenosine, a chemical that gradually builds up in the brain throughout the day and makes us feel increasingly sleepy the longer we stay awake. By occupying the receptors that adenosine would normally bind to, caffeine tricks the brain into feeling alert even when the body has accumulated significant sleep pressure. The effects, however, last far longer than most people realize. Because caffeine can remain active in the bloodstream for five to six hours, a cup of coffee consumed in the late afternoon may still be interfering with the ability to fall asleep at midnight. Even when people do not consciously notice difficulty falling asleep, _______________. For this reason, many sleep specialists advise avoiding caffeine after early afternoon.

Smartphones, tablets, and computer screens all emit a significant amount of blue light, a short-wavelength light that our eyes are especially sensitive to. During the day, exposure to blue light from the sun helps keep us alert and mentally sharp, which is generally beneficial. At night, however, the same wavelength can interfere with the body's natural preparation for sleep. Specialized cells in the retina detect blue light and send signals to the brain's internal clock, which results in _______________. 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. 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.

Melatonin is a hormone 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, 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 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, _______________, 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 intended.

Many students struggle not with lack of effort but with lack of structure when studying for exams. (A) Once colors are assigned, the student blocks specific hours of the day for each subject, following the same order as a printed timetable. (B) As a result, switching between subjects no longer feels confusing, because each color block signals exactly what should happen next. (C) One student solved this problem by giving each subject a distinct color on a printed weekly calendar before the semester began.

Breaking the bystander effect requires more than good intentions; it requires concrete action from those who witness cruelty online. (A) Simply reporting an abusive post to platform moderators, for example, can remove harmful content before it spreads further. (B) Even small gestures, such as privately messaging the victim with words of support, can reduce the isolation that targets of cyberbullying often feel. (C) Both of these actions demonstrate that individual witnesses possess more power to help than the bystander effect leads them to believe.

The twenty-hour rule has become popular among adults who want to pick up new hobbies despite busy schedules. (A) She practiced basic shading and proportion for about ninety minutes each day, carefully tracking her total hours. (B) A woman who always wanted to sketch, for example, decided to test the rule during a two-week vacation. (C) By the time she reached twenty hours, she could produce simple portraits that she was proud to share with friends.