영어 모의고사 (자동 편성)

Anyone who has ridden a bicycle after a decade away from one has likely ① experiencing muscle memory firsthand: the body seems to recall a complex skill almost instantly, even when conscious memory of the exact movements has faded. Contrary to what the name suggests, muscles themselves do not actually store memories; the phenomenon originates in the brain and nervous system, where repeated practice gradually ② shifts control of a well-learned movement from regions associated with conscious thought to areas that operate largely automatically. This shift explains why a skilled athlete can ③ execute a complicated sequence of movements without consciously thinking through each individual step, freeing mental attention for strategy and decision-making instead. Interestingly, research also suggests that these neural pathways can remain partially intact even after long periods without practice, which is why relearning a skill is typically much ④ faster than learning it for the very first time. Coaches often exploit this principle by ⑤ ensuring that fundamental techniques are practiced correctly from the very beginning.

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 shifts later, ① making it difficult for teenagers to fall asleep before eleven at night. Yet school start times rarely adjust to this shift, ② 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 ③ that regulating appetite, contributing to unhealthy weight gain over time. Some school districts have experimented with ④ 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 ⑤ remains a slow and contentious process.

Jina used to fill her apartment with items she rarely used, believing that owning more things would make her ①happier. After moving twice within a single year, she grew ②energized from packing boxes filled with clothes she had never worn and gadgets she had forgotten she owned. Gradually, however, she noticed that her small apartment felt ③calmer and easier to manage. She also realized that she spent significantly ④less money once she stopped buying things impulsively to fill emotional gaps. Jina's story reflects a broader trend among young adults who increasingly value experiences and simplicity over ⑤accumulating possessions.

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 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 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 _______________. A healthy night typically cycles through both stages four or five times, with non-REM dominating the early hours and REM periods lengthening toward morning. Disrupting either stage, through frequent awakenings or alcohol use, can leave a person feeling unrested even after a full night in bed.

When people consistently sleep too little, the body's hormonal balance shifts in ways that can quietly encourage weight gain. Two hormones in particular play 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 _______________, even after a normal-sized meal. 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. Because these effects build up so 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.

Colors carry different psychological associations that marketers use strategically when designing logos. (A) Red, for example, often appears in logos related to food and sales, since it tends to stimulate energy and urgency. (B) Blue, on the other hand, frequently appears in logos for banks and technology companies because it suggests trust and stability. (C) These associations, however, are not universal, since the same color can carry very different meanings across cultures.

Across many countries, high schools begin classes early in the morning, often before eight o'clock. (A) 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 adolescent ones. (B) This schedule assumes that teenagers can simply go to bed earlier to compensate, but biology tells a different story, because the body's internal clock shifts later during adolescence, delaying the release of melatonin until well after ten at night. (C) As a result, most teenagers are not physiologically ready to fall asleep until much later than adults, and when early start times force them to wake before completing a full sleep cycle, the mismatch accumulates into a chronic sleep debt.

Every cell in the human body follows an internal timer known as the circadian rhythm, a roughly twenty-four-hour cycle that governs when we feel alert and when we feel drowsy. (A) This clock is regulated primarily by a tiny cluster of neurons in the brain that responds to light entering through the eyes, signaling the body to suppress sleep hormones each morning. (B) As evening approaches and light fades, however, the same mechanism triggers the release of melatonin, a hormone that promotes drowsiness. (C) Because this rhythm evolved around the natural cycle of day and night, modern habits such as artificial light exposure or night shifts can push it out of sync, which has been linked to digestive problems and reduced concentration.

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. (A) 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. (B) Still other researchers argue that dreaming is simply a byproduct of the brain organizing memories rather than serving any independent purpose, and because these theories rest on indirect evidence, none has been conclusively proven, leading many scientists to suspect that dreaming may serve several functions simultaneously. (C) 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.

Its influence, in fact, can persist quietly long after any feeling of alertness has faded. 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. ( ① ) 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. ( ② ) 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. ( ③ ) 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. ( ④ ) Even when people do not consciously notice difficulty falling asleep, caffeine has been shown to reduce the amount of deep, restorative sleep obtained later in the night. ( ⑤ ) For this reason, many sleep specialists advise avoiding caffeine after early afternoon.