영어 모의고사 (자동 편성)

Online advertising algorithms analyze enormous amounts of user data ①to determine which products a person is most likely to purchase. Every click, search, and pause while scrolling provides information that these systems use ②to refine future advertisements. Supporters argue that this level of precision benefits consumers by ③reducing exposure to irrelevant advertisements and highlighting products they genuinely need. Critics, however, worry that constant exposure to tailored ads can encourage unnecessary spending, since algorithms ④is specifically designed to identify and exploit individual weaknesses. Greater transparency, many experts argue, would allow consumers ⑤to make more informed decisions about their own online behavior.

Sleep is not a single, uniform state but a cycle that alternates between two very different modes: REM (rapid eye movement) sleep and non-REM sleep. During non-REM sleep, especially its deepest stage, the brain waves ① slow down dramatically, the body temperature drops, and tissue repair and growth hormone release reach their peak. This is the period most closely associated with physical ② restoration. REM sleep, by contrast, brings rapid eye movements, near-total muscle paralysis, and brain activity that closely resembles wakefulness. Most vivid dreaming occurs during this stage, and researchers believe it plays a central role in ③ ignoring memories and processing emotional experiences. A healthy night typically cycles through both stages four or five times, with non-REM dominating the early hours and REM periods ④ lengthening toward morning. Disrupting either stage, through frequent awakenings or alcohol use, can leave a person feeling ⑤ unrested even after a full night in bed.

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 ① drowsy 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, ② suppressing the release of melatonin, the hormone that signals it is time to rest. Studies have found that people who scroll through their phones in bed before sleeping take longer to fall asleep and experience ③ lighter, more easily disrupted sleep than those who avoid screens. Some devices now offer a night mode that shifts the display toward ④ 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 ⑤ results.

Many people struggling to fall asleep in noisy environments turn to white noise machines, devices that emit a ① chaotic, uniform sound covering a broad range of frequencies. The appeal lies in a phenomenon called auditory masking, in which a constant background sound makes sudden noises, such as a slamming door, ② less noticeable to the sleeping brain. Without this masking effect, an abrupt change in sound is far more likely to trigger a brief awakening, even if the sleeper does not ③ consciously remember it the next morning. Studies comparing sleep in quiet rooms with sleep alongside white noise have found that participants using white noise experienced fewer of these brief awakenings and reported feeling more ④ rested. However, researchers caution that the benefit depends heavily on volume and consistency, since noise that is too loud or that varies unpredictably can itself become a source of ⑤ disruption rather than a remedy.

Insomnia is rarely caused by a single factor; it usually emerges from an interaction between psychological stress and physiological arousal that keeps the body from settling into sleep. A common trigger is what researchers call cognitive hyperarousal, in which _______________. At the same time, the body's stress response system can become chronically activated, 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 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 relying on medication alone.

Sleep hygiene refers to a set of simple daily habits that help the body prepare for consistent, restorative rest. Experts commonly recommend going to bed and waking up at the same time every day, even on weekends, because an irregular schedule confuses the body's internal clock and makes it harder to fall asleep on demand. They also advise reserving the bedroom for sleep alone, since using the bed to study, scroll through a phone, or watch videos teaches the brain to associate that space with wakeful activity rather than rest. Physical environment matters as well: a cool, dark, and quiet room tends to produce deeper sleep than one that is warm, bright, or noisy. None of these individual habits guarantees a good night's sleep on its own, but together they form a routine that _______________, much the way a consistent set of cues trains an athlete's body to perform at a certain time each day.

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.

Have you ever noticed your mood shifting after scrolling through a friend's gloomy post online? This phenomenon, known as emotional contagion, refers to the tendency of one person's feelings to spread to others nearby, almost like a cold passing between classmates. However, researchers have discovered that emotional contagion also occurs online, where only text or images are exchanged, without any physical presence at all. For instance, when someone posts a negative comment beneath a cheerful photo, the comments that follow often turn noticeably more negative in tone. In contrast, a single kind comment can shift an entire thread toward positivity within minutes. This suggests that emotions online spread through carefully chosen words alone. Consequently, many experts now argue that ___________.

After a strenuous workout, muscle fibers experience thousands of microscopic tears, and the body immediately begins a repair process that depends heavily on amino acids, the building blocks that protein supplies. (A) Waiting too long to eat, however, can slow this recovery, since a muscle's sensitivity to amino acids gradually declines once that window closes. (B) Even so, eating an enormous quantity of protein in a single sitting will not speed things up any further, because the body can only use a limited amount at once, burning or storing the rest. (C) This is precisely why sports scientists recommend consuming protein within a couple of hours after a workout, while the muscle is still especially receptive to it.

This is precisely what makes the condition so difficult to catch before it becomes severe. Ambitious young athletes and the parents who support them sometimes assume that more training automatically produces better results, a belief that occasionally leads to a condition known as overtraining syndrome. ( ① ) 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 producing persistent exhaustion, declining performance despite continued hard work, and increased susceptibility to illness and injury. ( ② ) Adolescents may be especially vulnerable, since their bodies are simultaneously coping with the physical demands of growth and the added stress of intensive training schedules. ( ③ ) 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 mistake for ordinary moodiness. ( ④ ) Recovery from full-blown overtraining syndrome can take months rather than days. ( ⑤ )