雅思阅读 54: The Unreckoned Cost of Lost Sleep（睡眠被剥夺的隐性代价）

改编自 Frontiers in Physiology / PMC 综述（2025年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2025.1732257/full

Reading Passage

A. Few modern habits are as common and as little regretted as going to bed late. A combination of shift work, cheap electric light, streamed entertainment and always-on messaging means that a large share of adults now sleep less than they did a generation ago, often by an hour or more each night. Sleep researchers have spent decades measuring what that lost hour actually does. What they have found is that sleep is not passive downtime but an active maintenance state: a period in which the brain replays memories, clears metabolic waste, and synchronises its internal timer — the circadian clock — with the outside world. That clock is not a single organ but a distributed system, with a master pacemaker in the brain and subordinate timers in the liver, pancreas, muscles and immune cells, each keeping its own schedule. When sleep is shortened, delayed or fragmented, all of those timers are asked to run out of step, and the body, it turns out, keeps a careful record of the mismatch. The consequences appear first in attention and mood, then in metabolism and immunity, and eventually in the slow deterioration of ageing tissue.

B. The most immediate effect of sleep loss is on the machinery of attention. In controlled experiments, volunteers kept awake for a night or given only a few hours of sleep show rising numbers of lapses on the Psychomotor Vigilance Test, a simple task that measures how quickly someone responds to a random light or tone. Those lapses are not the same as feeling tired; they are brief, involuntary failures of attention that last for seconds and are hard to correct once they begin. Studies of medical residents on rotating night shifts have found that such failures, combined with slowed decision-making, produce error rates comparable to those seen in people who have drunk enough alcohol to be legally intoxicated. Mood deteriorates in parallel: irritability, anxiety and an exaggerated response to emotional stimuli all rise after even a single night of insufficient sleep, and experiments in animals show that a fortnight of restricted sleep can alter the very brain regions that regulate emotion, producing changes that a later period of recovery sleep only partly reverses.

C. Sleep, it turns out, is also a pillar of the immune system. A 2025 study monitoring hundreds of healthy volunteers found that even a single night of total wakefulness was enough to change the behaviour of monocytes — white blood cells that form the front line of innate immunity. After one night without sleep, these cells adopted a more inflamed, more reactive profile, as though the body were preparing for injury that never arrived. Experiments lasting a week or two go further, showing that sleep loss disrupts the rhythm of so-called clock genes inside cells and ramps up inflammatory signalling pathways in the brain's emotional centres. The practical reading is that chronic sleep restriction is not merely tiring; it quietly pushes the immune system toward a state of low-grade inflammation, the kind of persistent, smouldering response that doctors now associate with a wide range of chronic diseases. This is one reason that long-term sleep shortfall is now treated not as a nuisance but as a plausible contributor to illness.

D. The long-term studies point in the same direction. People who work permanent night shifts live with a circadian system that is almost permanently misaligned: their internal clock says "day" while their schedule demands sleep, and the clocks in their liver and pancreas follow suit. Population studies have consistently linked this chronic misalignment to a higher risk of obesity, insulin resistance and type 2 diabetes, because the timing of hormone release and digestion is thrown out of rhythm. Even more striking is the accumulating evidence on neurodegeneration. In animal models, disrupted sleep-wake cycles accelerate the accumulation of amyloid-beta, the protein that clumps into plaques in Alzheimer's disease, and worsen the tangles of tau protein that follow. In humans, disturbed sleep and wandering circadian rhythms appear years before dementia becomes obvious, leading researchers to suspect that the relationship runs in both directions: poor sleep feeds the disease, and the disease then further erodes sleep. Sleep, in other words, may be one of the few modifiable habits that influence whether a damaged brain repairs itself.

E. Not all hope is lost, but recovery is more complicated than simply sleeping in at the weekend. A 2025 comparison of military cadets who were kept awake in light versus darkness found that sleep deprivation disrupted the daily rhythms of body temperature and physical activity in both groups, but that those who recovered in darkness returned to their normal rhythms far more quickly. Those who recovered in bright light remained misaligned even five days later, suggesting that the timing and brightness of light during recovery matter as much as the number of hours asleep. This is the kind of finding that translates awkwardly into advice, because most people cannot simply choose to recover in a darkened room. What it does suggest, though, is that a society chronically short on sleep cannot solve the problem with caffeine alone. Caffeine, after all, only masks the signal that the brain sends to demand sleep; it does not perform the housekeeping that sleep itself accomplishes, the clearing of metabolic waste and the resetting of hormone rhythms. The body keeps a ledger, and the longer its clocks run out of step, the more expensive the repayment becomes. Policymakers, employers and schools are only beginning to take that ledger seriously — shifting start times, discouraging all-night shifts, and treating sleep as a public-health issue rather than a private indulgence. Whether those measures arrive in time to matter for a generation that has been taught to wear exhaustion as a badge of efficiency is, in the end, the question that all this research is quietly asking.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. Attention lapses and the emotional toll of fatigue ii. How wakefulness overnight rewires the immune response iii. Long-term links to metabolism and the ageing brain iv. Why recovery is not as simple as sleeping in v. A brief history of the alarm clock vi. How sleep laboratories are equipped vii. The global trade in coffee beans

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What did the comparison of sleep recovery in light versus darkness find? A. Recovery in bright light restored normal rhythms within a day. B. Recovery in darkness allowed a faster return to normal rhythms. C. Neither group showed any sign of recovery. D. Body temperature rose permanently in both groups.

6. How do researchers describe the effect of sleep loss on medical residents? A. It has no measurable effect on their work. B. Their error rates resemble those of people who are intoxicated. C. It makes their decision-making faster. D. It removes the need for caffeine.

7. What did the 2025 study of healthy volunteers find after one sleepless night? A. Monocytes became more inflamed and reactive. B. The immune system became permanently stronger. C. Antibody levels doubled overnight. D. No change was detectable in white blood cells.

8. Chronic circadian misalignment in shift workers is associated with a higher risk of... A. improved eyesight. B. obesity, insulin resistance and type 2 diabetes. C. faster healing of wounds. D. deeper sleep at weekends.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Sleep deprivation disrupts the daily rhythms of body temperature and physical activity.
10. Cadets who recovered in bright light had fully realigned their rhythms within five days.
11. In animal models, disturbed sleep-wake cycles accelerate the accumulation of amyloid-beta.
12. Two weeks of restricted sleep produces changes that are always completely reversed by one night of recovery.
13. The average adult now needs fewer than four hours of sleep each night.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

A single sleepless night alters the behaviour of white blood cells called (14) __________, pushing the body toward low-grade inflammation, while long-term misalignment is associated with (15) __________ resistance and type 2 diabetes.

答案与解析

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