Practice Tests
IELTS Reading (AC) Task 1 #152

A. Sleep is a fundamental biological process that is essential for physical and mental health, yet its precise functions have long been a subject of scientific inquiry. Modern sleep science has begun to unravel the complex mechanisms and vital roles of sleep, revealing it to be an active and dynamic period of intense neurological activity. Far from being a passive state of rest, sleep is critical for a wide range of functions, including memory consolidation, cellular repair, and emotional regulation.

B. During sleep, the brain cycles through several stages, broadly categorised into non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Each stage plays a distinct role. During the deep stages of NREM sleep, the body carries out physical restoration, repairing tissues, building bone and muscle, and strengthening the immune system. REM sleep, the stage most associated with vivid dreaming, is crucial for cognitive functions, including learning, memory consolidation, and emotional processing.

C. One of the most important functions of sleep is its role in memory. While we sleep, the brain processes and consolidates the information and experiences from the day, transferring memories from short-term to long-term storage. This is why adequate sleep is vital for effective learning and academic performance. Sleep also performs a critical "housekeeping" function for the brain, clearing out metabolic waste products that accumulate during waking hours, a process which may be important for preventing neurodegenerative diseases.

D. Chronic sleep deprivation, a common problem in modern society, can have severe consequences for health and well-being. It can impair cognitive function, attention, and decision-making, and is linked to an increased risk of numerous health problems, including obesity, diabetes, cardiovascular disease, and mood disorders. Growing awareness of sleep''s importance is leading to a greater emphasis on "sleep hygiene"—practices and habits that are conducive to sleeping well on a regular basis—as a cornerstone of a healthy lifestyle.