IELTS Academic Reading Practice Test 3

For as long as people have travelled by sea, coasts have been both a destination and a danger. Rocks, sandbanks and headlands that are easily avoided in daylight become treacherous at night or in severe weather, and for centuries the only warning available to a vessel might be a beacon fire maintained on a hilltop by the local population. The most famous early lighthouse, the Pharos of Alexandria, was completed in the third century BCE and is thought to have stood more than 100 metres high, with a fire burning at its summit. It survived for well over a thousand years before a series of earthquakes reduced it to ruins. Its reputation was such that the word for 'lighthouse' in several Mediterranean languages, including the French 'phare' and the Italian 'faro', derives from its name.

Building a lighthouse on land was one thing; building one on a rock in the open sea was quite another. The Eddystone reef, about 20 kilometres off the coast of south-west England, had wrecked so many ships that several attempts were made to mark it. The first tower, built of wood by Henry Winstanley and lit in 1698, was swept away together with its designer during a violent storm in 1703. A second wooden tower stood for almost fifty years until it was destroyed by fire in 1755.

The engineer John Smeaton, who was asked to design its replacement, approached the problem in a new way. Instead of wood, he chose stone, and he modelled the shape of his tower on the trunk of an oak tree, which is wide at the base and narrows as it rises – a form that resists the force of the waves.

The foundations and outer walls were built from granite, and each block was cut so that it locked into its neighbours with dovetail joints, making the structure behave almost like a single piece of rock. Smeaton also experimented with different kinds of lime until he found a mortar that would set even when it was wet with seawater. His tower was first lit in 1759, by twenty-four candles, and it stood for more than a century. It was replaced only because the rock beneath it had begun to wear away, and its upper part was taken down and rebuilt on land in Plymouth, where it can still be visited.

Brighter lights required better optics as well as stronger towers. Early lamps sent much of their light upwards or down into the sea, where it was wasted. Mirrors helped, but a breakthrough came in 1822, when the French physicist Augustin Fresnel designed a lens made up of many separate pieces of glass arranged in rings. The underlying principle had been suggested in the previous century, but Fresnel was the first to combine it with a rigorous mathematical analysis of the behaviour of light, which allowed each component to be manufactured with the necessary precision.

The central part focused the light like an ordinary lens, while the outer rings of prisms bent the remaining light so that it, too, travelled out towards the horizon in a narrow, powerful beam. Because it was built from thin sections rather than one thick block of glass, the lens was much lighter than a conventional lens of the same size. The first was installed in 1823 in the Cordouan lighthouse at the mouth of the Gironde estuary in France, and within a few decades Fresnel lenses had been fitted in lighthouses around the world.

In a typical nineteenth-century lighthouse, the lens and lamp were housed in the lantern, a glass-walled room at the very top of the tower. Outside it ran a narrow gallery, a walkway from which the keepers cleaned salt and soot from the windows. To make each lighthouse recognisable, many lights were designed to flash in a particular pattern, which was achieved by rotating the lens.

The power came from heavy weights that slowly descended through a tube running down the centre of the tower, driving a clockwork mechanism; the keepers had to wind the weights back up at regular intervals through the night. Towards the end of the century, engineers found that the lens could be turned far more easily, and therefore faster, if it floated on a bath of mercury, a liquid metal dense enough to support the great weight of the glass.

The keepers' work was demanding and often lonely, especially on offshore towers, where they might be cut off by bad weather for weeks. Their duties, set out in detailed regulations issued by the authorities responsible for navigation, included maintaining a continuous watch and recording meteorological observations. Gradually, however, technology removed the need for them. Electric lamps, automatic switches and remote monitoring meant that lights could be operated without anyone present, and in Britain the last lighthouse keepers left their post at North Foreland in Kent in 1998. Today, satellite navigation means that ships rarely depend on lighthouses to find their position, yet many lights are still maintained as a back-up, and the towers themselves have become cherished landmarks.

Most people know from experience that a poor night's sleep makes it harder to think clearly the following day. Less obvious is the role that sleep plays after learning has taken place. Over the past century, and particularly in the last few decades, researchers have built up a substantial body of evidence suggesting that sleep is not simply a period of rest for the brain, but an active state in which newly acquired memories are stabilised, reorganised and strengthened. The implications extend well beyond the laboratory, influencing how students prepare for examinations and even how educational institutions organise the school day.

The question has a long history. In 1885 the German psychologist Hermann Ebbinghaus published a study of his own memory, in which he learned lists of meaningless syllables and measured how quickly he forgot them. His results produced what became known as the forgetting curve, showing that most forgetting happens soon after learning. Almost forty years later, in 1924, two American researchers, John Jenkins and Karl Dallenbach, examined whether sleep made a difference. Their participants, two university students, learned material and were then either kept awake or allowed to sleep before being tested, and they remembered considerably more after sleeping. Jenkins and Dallenbach concluded that forgetting was caused less by the simple passage of time than by interference from new experiences while awake – in other words, that sleep protected memories by shielding them from disruption.

For several decades afterwards, sleep was widely regarded as a single, uniform state. That view changed in 1953, when Eugene Aserinsky and Nathaniel Kleitman at the University of Chicago reported that sleepers periodically entered a phase in which their eyes moved rapidly beneath closed lids, their brain activity resembled that of a waking person, and – as later studies showed – they were most likely to report vivid dreams if woken. This rapid eye movement, or REM, sleep alternates through the night with non-REM sleep, which includes a deep phase known as slow-wave sleep, characterised by large, slow electrical waves across the brain. Over a typical night, a healthy adult passes through four or five such cycles, each lasting roughly ninety minutes, with periods of REM sleep becoming progressively longer towards the morning.

Animal studies provided some of the most striking evidence of what happens to memories during these stages. In the 1990s, researchers recording the activity of individual brain cells in rats found that cells in the hippocampus, a region essential for forming new memories, fired in particular sequences as the animals explored a maze. When the rats later slept, the same sequences reappeared, as if the brain were replaying the day's experience. Many scientists now believe that such replay, which occurs mainly during slow-wave sleep, helps to transfer information from the hippocampus to the outer layer of the brain, the cortex, where it can be stored for the long term. Comparable patterns of replay have since been identified in other species, and techniques capable of detecting related activity in humans suggest that the process is not confined to rodents.

Different kinds of memory may depend on different stages of sleep. Memory for facts and events appears to benefit particularly from slow-wave sleep, while some studies have linked REM sleep to emotional memory and to the ability to find hidden patterns or solutions in information. The evidence is not entirely consistent, however, and some researchers argue that it is the combination and sequence of sleep stages across the night, rather than any single stage, that matters most. Some experimenters have even attempted to influence this consolidation directly, for instance by quietly replaying sounds or odours during sleep that had previously been associated with particular information, with modest but measurable effects on subsequent recall.

Sleep may matter before learning as well as afterwards. In experiments in which volunteers were deprived of a night's sleep and then asked to memorise pictures, they performed noticeably worse than well-rested participants, and brain scans showed reduced activity in the hippocampus. This suggests that staying up all night to revise for an examination – a common habit among students – may be counterproductive, since it weakens the brain's ability to take in the very information the student is trying to learn. The consequences are not confined to memory: insufficient sleep also impairs attention, judgement and emotional regulation, all of which contribute to academic performance.

These findings have practical consequences. Teenagers, for biological reasons, tend to fall asleep and wake up later than younger children and adults, yet many secondary schools begin early in the morning. In 2014 the American Academy of Pediatrics recommended that middle and high schools should not start before 8.30 a.m., arguing that the change would help students obtain enough sleep. Some school districts that have adopted later start times have reported improvements in attendance and alertness, although measuring the effect on academic results has proved more difficult. Researchers point out that many other factors, from the quality of teaching to students' family circumstances, also influence results, which makes the contribution of sleep hard to isolate.

The idea that people should work fewer hours is not new. In 1930 the economist John Maynard Keynes predicted that, within a century, rising productivity would allow people in wealthy countries to work as little as fifteen hours a week. For much of the twentieth century, working hours did indeed fall, and the five-day week, which a few large employers had adopted in the 1920s, gradually became the norm. Henry Ford, whose car factories were among the first to introduce it, argued that employees with more leisure would also become more active consumers, an early example of the claim that shorter hours could benefit employers as well as workers. Since the 1980s, however, average hours in many developed economies have fallen far more slowly, and Keynes's prediction now looks remarkably optimistic.

In recent years the four-day week has nevertheless moved from the margins of political debate into the mainstream, largely as a result of a series of trials. In 2019 Microsoft's Japanese subsidiary gave its employees every Friday off during one summer month and reported that sales per employee rose by nearly 40 per cent compared with the same month a year earlier. Between 2015 and 2019, two large trials in Iceland moved around 2,500 public-sector workers to shorter weeks without any reduction in pay, and the researchers who analysed the results reported that productivity and the quality of services stayed the same or improved in most of the workplaces involved.

The largest coordinated trial took place in the United Kingdom in the second half of 2022, when 61 companies employing around 2,900 people reduced working time, typically to four days, while keeping pay the same. At the end of the six months, 56 of the companies said they would continue with the arrangement, and 18 said the change would be permanent. Staff reported lower levels of stress and burnout and better sleep, and the number of employees leaving the participating companies fell sharply compared with the previous year.

Supporters argue that these results reveal something important about modern work. In many offices, they suggest, a significant share of the working week is lost to unnecessary meetings, interruptions and tasks of little value, and a shorter week forces organisations to identify and remove them. Rested employees, they add, make fewer mistakes and are less likely to fall ill or to leave, which saves employers the considerable cost of recruiting and training replacements. Some economists go further, suggesting that a shorter week could distribute available work more evenly across the population, although this argument has attracted considerable scepticism.

Critics, however, have raised several objections. The companies that take part in trials do so voluntarily, and they are likely to be those that already expect the change to work; their experience may tell us little about what would happen if a four-day week were introduced across an entire economy. Much of the evidence also comes from surveys of employees, who may naturally view a reduction in their hours favourably.

Moreover, measuring productivity is relatively straightforward in sales or manufacturing but far more difficult in occupations such as teaching or nursing, where output cannot easily be counted and where a shorter week for each employee may simply mean hiring more staff. There is also the question of whether initial improvements will persist once the novelty has faded, since employees who know they are participating in an experiment may temporarily work harder than they otherwise would.

These objections are reasonable, but they do not justify dismissing the idea. It is true that the early trials have not been carried out under ideal scientific conditions, and that their organisers have often been enthusiastic advocates of shorter hours. Yet the consistency of the findings across different countries and industries is difficult to ignore. What the evidence does not support is the claim that a single model will suit every organisation.

A hospital cannot simply close on Fridays, and a small business with a handful of staff may struggle to cover absences. The most realistic outcome is not that the four-day week will replace the five-day week everywhere, but that it will become one of several ways of organising work, alongside part-time contracts, flexible hours and remote working. Its adoption is therefore likely to be uneven, concentrated initially in office-based sectors where output is easier to define and where employers compete intensively for skilled staff.

Perhaps the most significant lesson of the trials is that the length of the working week is a choice rather than a law of nature. The five-day week itself was once a radical experiment. Whether a further reduction becomes common will depend less on evidence from pilot schemes than on the decisions of governments, employers and employees about how the benefits of rising productivity should be shared.