睡前刷手机，代价不止是缺觉
Many teenagers keep their phones within reach at night. They text friends, watch videos, or scroll through social media long after they should have turned out the light, often later than planned. A recent study suggests that this bedtime habit may come at a cost: researchers linked it not only to shorter sleep but also to low mood, worry and even anxiety. For young people especially, sleep is far from wasted time — it is when the body grows and the brain stores what has been learned that day.
In the study, researchers compared thousands of teenagers who used their phones late at night with those who did not. Those who did went to bed later and were more likely to report feeling sad, worried or lonely, and the longer they stayed online past midnight, the stronger the effect appeared to be. Taken together, the findings suggest that timing may matter as much as total screen time: even a few minutes of scrolling can leave the brain buzzing at an hour when it should be winding down.
Why, then, is using a phone in the small hours so damaging? Bright screens are part of the answer, but probably not the main one. What keeps teenagers awake is more often the content itself — the next video, the next message, the notifications arriving just as teenagers are dropping off. Robbed of sleep, they struggle to concentrate in class, and a tired brain finds it far harder to manage emotions.
So what can be done? Parents can agree on clear rules with their children — charging phones outside the bedroom, for instance, and switching screens off an hour before bed. Teenagers themselves can replace late-night scrolling with quieter activities such as reading or listening to soft music. The aim is not to ban phones but to build habits young people can actually keep. None of this works overnight, but with patience and practice they will find it easier to put their screens down — and to notice the difference in their mood, their energy and their schoolwork.
1.1. According to the recent study in Paragraph 1, what did the bedtime phone habit cause?
A Sharper focus each morning.
B Less sleep, poorer mood.
C Closer friendship with others.
D Quicker body development.
解析：选B。B 细节理解题。原文第一段明确说明研究将睡前使用手机的习惯与“shorter sleep”（睡眠更短）和“low mood, worry and even anxiety”（情绪更低落、担忧甚至焦虑）联系起来，选项 B “Less sleep, poorer mood”为其同义改写。A项“Sharper focus each morning”（早晨注意力更集中）与原文相反——后文指出缺觉会让人上课难以集中；C项“Closer friendship with others”（与朋友关系更亲密）属无中生有，文中未提及；D项“Quicker body development”（身体发育更快）与原文相反，文中强调身体发育发生在睡眠中，而非手机使用带来的结果。故选B。
2.2. What did researchers find about the timing of late phone use?
A Total time is the only factor.
B Morning use harms mood most.
C Timing matters as much as length.
D Brief use causes no harm.
解析：选C。C 细节理解题。第二段末句指出“timing may matter as much as total screen time”，即使用手机的时间点（timing）和总时长（length）同样重要，选项C为其同义改写。A项“Total time is the only factor”（总时长是唯一因素）表述绝对化，与原文“同样重要”相悖；B项“Morning use harms mood most”（早晨使用对情绪伤害最大）属无中生有，文中只讨论深夜使用；D项“Brief use causes no harm”（短暂使用无害）与原文相反，文中明确说“even a few minutes of scrolling can leave the brain buzzing”（哪怕几分钟也会让大脑兴奋难眠）。故选C。
3.3. What does the underlined phrase “dropping off” in Paragraph 3 most probably mean?
A Losing the phone signal.
B Growing angry with others.
C Putting the device away.
D Falling slowly into sleep.
解析：选D。D 词义猜测题。第三段语境为“The notifications arriving just as they are dropping off”，前文说“是什么让青少年保持清醒”，紧接着描述通知在“dropping off”时到来，结合“保持清醒”的反向逻辑及“临近入睡”的语义，可推断dropping off意为“渐渐入睡”，选项D“Falling slowly into sleep”正确。 A项“Losing the phone signal”（手机失去信号）、B项“Growing angry with others”（对他人生气）、C项“Putting the device away”（把设备收起来）均与上下文无关，属无中生有。故选D。
4.4. What can we infer from the last paragraph?
A Good habits need time to form.
B Phones must be banned at home.
C Parents should take all devices.
D Teens never follow any rules.
解析：选A。A 推理判断题。最后一段指出建立良好习惯“None of this works overnight, but with patience and practice”（不会一蹴而就，需要耐心与练习），由此可推断好习惯的形成需要时间，选项A正确。B项“Phones must be banned at home”（家里必须禁用手机）与原文相反，文中明确“aim is not to ban phones”（目的不是禁用手机）；C项“Parents should take all devices”（父母应收走所有设备）以偏概全且表述绝对，文中仅建议“charging phones outside the bedroom”等具体规则，并非收走一切；D项“Teens never follow any rules”（青少年从不遵守任何规则）表述绝对化且与原文鼓励青少年养成习惯的基调相悖。故选A。