Sleep Why We Sleep Reading Answers with Explanation

IELTS Reading Passage: Sleep Why We Sleep

Paragraph A

As the field of sleep research is still relatively new, scientists have yet to determine exactly why people sleep. However, they do know that humans must sleep and, in fact, people can survive longer without food than without sleep. And people are not alone in this need. All mammals, reptiles, and birds sleep.

Paragraph B

Scientists have proposed the following theories on why humans require sleep:

• Sleep may be a way of recharging the brain. The brain has a chance to shut down and repair neurons and to exercise important neuronal connections that might otherwise deteriorate due to lack of activity.
• Sleep gives the brain an opportunity to reorganise data to help find a solution to problems, process newly learned information, and organise and archive memories.
• Sleep lowers a person's metabolic rate and energy consumption.
• The cardiovascular system also gets a break during sleep. Researchers have found that people with normal or high blood pressure experience a 20 to 30% reduction in blood pressure and a 10 to 20% reduction in heart rate.
• During sleep, the body has a chance to replace chemicals and repair muscles, other tissues, and aging or dead cells.
• In children and teenagers, growth hormones are released during deep sleep.

Paragraph C

When a person falls asleep and wakes up is largely determined by his or her circadian rhythm, a day-night cycle of about 24 hours. Circadian rhythms greatly influence the timing, amount, and quality of sleep.

For many small mammals such as rodents, sleep has other particular benefits, as it provides the only real opportunity for physical rest, and confines the animal to the thermal insulation of a nest. In these respects, sleep conserves much energy in such mammals, particularly as sleep can also develop into a torpor, whereby the metabolic rate drops significantly for a few hours during the sleep period. On the other hand, humans can usually rest and relax quite adequately during wakefulness, and there is only a modest further energy saving to be gained by sleeping. We do not enter torpor, and the fall in metabolic rate for a human adult sleeping compared to lying resting but awake is only about 5-10%.

Paragraph D

A sizeable portion of the workforce is shift workers who work and sleep against their bodies' natural sleep-wake cycle. While a person's circadian rhythm cannot be ignored or reprogrammed, the cycle can be altered by the timing of things such as naps, exercise, bedtime, travel to a different time zone, and exposure to light. The more stable and consistent the cycle is, the better the person sleeps. Disruption of circadian rhythms has even been found to cause mania in people with bipolar disorder.

Paragraph E

The 'seven deadly sins' formulated by the medieval monks included Sloth. The Bible in Proverbs 6:9 includes the line: 'How long will you sleep, O sluggard? When will you arise out of your sleep?' But a more nuanced understanding of sloth sees it as an inclination to labour or work. This isn't the same as the desire for healthy sleep. On the contrary, a person can't work without rest periods, and no one can operate at top performance without adequate sleep. The puritan work ethic can be adhered to, and respect still paid to the sleep needs of healthy humans. It is wrong to see sleep as a shameful activity.

Paragraph F

Usually, sleepers pass through five stages: 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress cyclically from 1 through REM then begin again. A complete sleep cycle takes an average of 90 to 110 minutes. The first sleep cycles each night have relatively short REM periods and long periods of deep sleep, but later in the night, REM periods lengthen and deep sleep time decreases. Stage 1 is light sleep, where you drift in and out of sleep and can be awakened easily. In this stage, the eyes move slowly, and muscle activity slows. During this stage, many people experience sudden muscle contractions preceded by a sensation of falling. In stage 2, eye movement stops, and brain waves become slower with only an occasional burst of rapid brain waves. When a person enters stage 3, extremely slow brain waves called delta waves are interspersed with smaller, faster waves. In stage 4, the brain produces delta waves almost exclusively. Stages 3 and 4 are referred to as deep sleep, and it is very difficult to wake someone from them. In deep sleep, there is no eye movement or muscle activity. This is when some children experience bedwetting, sleepwalking, or night terrors.

Paragraph G

In the REM period, breathing becomes more rapid, irregular, and shallow, eyes jerk rapidly, and limb muscles are temporarily paralysed. Brain waves during this stage increase to levels experienced when a person is awake. Also, heart rate increases, blood pressure rises, and the body loses some of the ability to regulate its temperature. This is the time when most dreams occur, and, if awoken during REM sleep, a person can remember their dreams. Most people experience three to five intervals of REM sleep each night. Infants spend almost 50% of their time in REM sleep. Adults spend nearly half of sleep time in stage 2, about 20% in REM, and the other 30% is divided between the other three stages. Older adults spend progressively less time in REM sleep.

Paragraph H

As sleep research is still a relatively young field, scientists did not discover REM sleep until 1953, when new machines were developed to monitor brain activity. Before this discovery, it was believed that most brain activities ceased during sleep. Since then, scientists have also disproved the idea that deprivation of REM sleep can lead to insanity and have found that lack of REM sleep can alleviate clinical depression, although they do not know why. Recent theories link REM sleep to learning and memory.

Questions for Reading Passage: Sleep Why We Sleep

Question 1-4

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

1. Among other functions, sleep serves to

A. help the adult body develop physically.

B. push daily problems from our minds.

C. accelerate the learning process significantly.

D. re-energise parts of the brain.

2. 'Torpor' can be described as

A. a very deep sleep.

B. a long state of hibernation.

C. the sleep all non-human mammals experience.

D. a light sleep

3. Unlike small mammals, humans

A. don't sleep to conserve energy.

B. don't sleep properly.

C. save only a small amount of energy by sleeping.

D. show no decrease in their metabolic rate when they sleep.

4. In stage 3 deep sleep

A. the eyes move slowly, and there's little muscle activity.

B. there is an alternation of delta waves and small fast waves.

C. there is an occasional burst of rapid brain waves.

D. there are no small fast waves.

Questions 6-9

Complete the flow-chart below.

Write NO MORE THAN THREE WORDS for each answer.

Questions 10-14

Complete the summary.

Choose NO MORE THAN TWO WORDS from the passage for each answer.

Sleep is so essential to a person that he can actually go longer without food than without sleep. During sleep, the brain has the chance to close down and do some repair work on neuronal connections, which could otherwise 10__ in a state of inactivity. Sleep also gives the brain the opportunity to organise data, especially newly learned information. During this rest period, the 11__ Drops and energy consumption go down. At the same time, the cardiovascular system has a much-needed rest. While they go into a deep sleep, humans don't fall into 12__, unlike some small animals such as rodents. A 13__ of 24 hours is described as a person's 14__, and this greatly influences a person's amount of sleep and the type of sleep he gets.