Why Do We Need Sleep?
Read Why Do We Need Sleep? and check the IELTS Reading answers. According to the United States (U.S.) Centers for Disease Control and Prevention (CDC), more than 80 million American adults are chronically sleep deprived, meaning they sleep less than the recommended minimum of seven hours a night. T…
Passage preview
According to the United States (U.S.) Centers for Disease Control and Prevention (CDC), more than 80 million American adults are chronically sleep deprived, meaning they sleep less than the recommended minimum of seven hours a night. The resulting fatigue contributes to more than a million auto accidents each year, as well as to a significant number of medical errors. Even small adjustments in sleep can be problematic. The Monday after a daylight-saving time change in the U.S. - when the clocks are moved ahead one hour - there is a 24 percent increase in heart attacks and a jump in fatal car crashes, compared with other Mondays.
Vocabulary from this passage
11 words worth learning before you sit the test, each with the sentence it appears in.
- cerebral cortex noun
The outer layer of the brain responsible for high-level processes like thought, memory, and voluntary action
Damage to the cerebral cortex can result in significant difficulties with speech and motor skill coordination.
- chronically adverb
In a way that continues or recurs over a long period; persisting for an extended duration
Patients who are chronically ill often require specialized long-term care plans to manage their ongoing medical needs.
- cognitive function noun
The mental processes involved in gaining knowledge and comprehension, including thinking, knowing, remembering, and judging
Maintaining a balanced diet and regular physical activity can help preserve cognitive function in the elderly.
- counteract verb
To act in opposition to something in order to neutralize or reduce its force or effects
The government introduced tax incentives to counteract the negative effects of the recent industrial decline.
- endow verb
To provide or equip naturally with a particular quality, talent, or physical characteristic
Nature has endowed certain bird species with vibrant plumage to help them attract potential mates during spring.
- pharmaceutical noun
A compound or substance manufactured for use as a medicinal drug or treatment
The pharmaceutical industry is constantly researching new ways to treat rare genetic conditions using gene therapy.
- prevalent adjective
Widespread or commonly occurring within a particular area, group, or period of time
The use of social media has become increasingly prevalent among all age groups in contemporary society.
- reverberate verb
To be repeated as an echo; to have a continuous and powerful effect or influence
The economic impact of the new trade policy will likely reverberate through the global market for decades.
- sleep apnea noun
A potentially serious sleep disorder where breathing repeatedly stops and starts during the night
Many patients with undiagnosed sleep apnea experience extreme daytime fatigue and a loss of concentration.
- sleep deprivation noun
The condition of not having enough sleep, which can lead to serious physical and cognitive impairments
Severe sleep deprivation can cause hallucinations and a significant decline in an individual's ability to perform tasks.
- unethical adjective
Not conforming to high moral standards or accepted principles of right and wrong behavior
The committee ruled that the proposed medical trial was unethical due to the lack of informed consent.
Answers with explanations
- 14. D
The question asks for a paragraph with an example of sleeplessness influencing someone accused of a crime. Paragraph D provides this by stating that **sleep-deprived suspects** held by police will often **confess to anything** just to get rest.
- 15. E
The question seeks a description of brain activity recordings. Paragraph E extensively details how an **EEG machine measures electrical impulses**, outlining distinct patterns like 'electric sparks' and 'big, rolling waves' across different stages of sleep.
- 16. C
The question asks how present-day society interrupts sleep. Paragraph C explicitly discusses the **modern world**, listing contemporary triggers like **worrying about an exam** or a **car alarm** that constantly trigger our wake-up call.
- 17. D
The question looks for information connecting being overweight and sleep. Paragraph D explicitly confirms that lack of sleep is **directly tied to obesity** due to the overproduction of the hunger hormone, causing people to eat more.
- 18. G
The question asks where medication is suggested as an ineffective solution. Paragraph G directly states that sleep loss is not easily solved by **pharmaceuticals** and warns against attempting to artificially manipulate sleep with **drugs**.
- 19. F
The question asks for a discovery that changed the understanding of sleep. Paragraph F explains that REM was initially thought to be insignificant, but once scientists **documented the distinctive eye movements**, it was newly recognized as the **second major phase** of sleep.
- 20. A
The question requires examples of life-threatening consequences of inadequate sleep. Paragraph A outlines severe, life-threatening results of fatigue, including a 24 percent increase in **heart attacks** and a jump in **fatal car crashes**.
- 21-22: BE
21: Option B is correct because the text describes REM sleep as having **distinctive eye movements**, matching the idea of an 'unusual physical feature.' Option E is correct because theorists believe REM makes us **creative and insightful**, making it a source of human innovation. Other options are contradicted or not supported.
22: Option E is correct because theorists argue REM sleep is when humans are most **intelligent, insightful, and creative**, supporting it as a source of innovation. Option B is also correct due to the 'distinctive eye movements'. The passage contradicts D (it's distinct from NREM) and does not support A or C.
- 23. ["fatal","car","auto"]
The sentence requires an adjective or noun modifying 'crashes' based on CDC data. The text states that fatigue from lack of sleep contributes to a jump in **fatal car crashes** or million **auto accidents**. Fatal, car, or auto are all acceptable words.
- 24. insomnia
The blank requires the name of a disorder. The text explicitly identifies **insomnia** as 'by far the most prevalent' (which means most common) sleep problem in the U.S.
- 25. emergency
The blank requires a singular noun that triggers the brain's alarm. The passage states that the brain's automatic override system activates when it perceives an **emergency**, waking us up.
- 26. depression
The blank requires a specific illness that sleep-deprived people are more likely to suffer from. The text notes an elevated risk of developing **depression**, alongside other mental and physical illnesses.