IELTS Reading Practice Test #19

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Jet lag is a phenomenon that affects millions of travelers each year, especially those who cross multiple time zones in a short period. It is characterized by a range of symptoms including fatigue, irritability, insomnia, and digestive issues. The condition occurs when a person’s internal biological clock—known as the circadian rhythm—falls out of sync with the local time at their destination. This misalignment can disrupt bodily functions and mental performance, often taking several days to correct.

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The body’s circadian rhythm is regulated by a small region in the brain called the suprachiasmatic nucleus, or SCN, located in the hypothalamus. This structure receives direct input from the eyes and adjusts the body’s rhythm according to the light and dark cycles of the environment. However, when someone quickly travels across several time zones, the SCN cannot immediately recalibrate. As a result, the body continues to operate on the original time zone, creating a disconnect between biological time and local time.

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Interestingly, the direction of travel plays a significant role in the severity of jet lag. Research has shown that traveling eastward—such as from New York to Paris—tends to produce more intense symptoms than traveling westward. This is because it is generally easier for the body to lengthen its internal day than to shorten it. Our natural circadian rhythm is slightly longer than 24 hours, making it simpler to delay sleep than to advance it. For this reason, westward travel tends to be less disruptive.

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Jet lag doesn’t just impact sleep; it also affects hormones, digestion, and cognitive function. Melatonin, a hormone that helps regulate sleep, is typically released in response to darkness. When a person is exposed to light at times that do not match their internal clock, melatonin secretion is disrupted. This leads to difficulty falling asleep or waking at appropriate times. Likewise, the digestive system, which is influenced by circadian patterns, can become confused, resulting in appetite loss or gastrointestinal discomfort.

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To counter the effects of jet lag, several strategies have been developed. Light exposure is perhaps the most powerful tool. Travelers are advised to get natural sunlight at specific times of day depending on the direction of travel. This can help reset the SCN and align the circadian rhythm with the new time zone. In some cases, controlled use of artificial light or light therapy lamps is recommended. Additionally, melatonin supplements are commonly used to shift sleep cycles. However, the effectiveness of melatonin depends on the timing of dosage, and improper use can exacerbate symptoms rather than relieve them.

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Airlines and travel experts are increasingly aware of jet lag’s impact on business travelers and tourists alike. Some airlines have experimented with cabin lighting that mimics natural light patterns during long-haul flights, and hotel chains often offer jet lag recovery programs that include exercise, meal timing, and sleep hygiene tips. Despite these efforts, no universal remedy exists, as individual responses to jet lag vary widely based on age, health, travel history, and personal habits. What works well for one person may not be effective for another, which underscores the importance of preparation and experimentation when crossing time zones.