Unit 4 reading techniques

I

The text below deals with recent research into sleep. Read it paying attention to the italisized link-words. Translate them into Russian.

Much research has been carried out in recent years into sleep. We know a great deal about the mechanics of sleep and we are beginning to know about the biochemical changes involved. However, we are still a long way from finding out answers to such questions as how much sleep a person needs. While the physiological basis of sleep remains very much a matter for conjecture (догадка) we do nevertheless have considerable evidence (данные) on how much sleep people obtain. Despite this we need to know more about the kinds of effect that sleep deprivation (лишение) causes. In spite of considerable effort devoted to investigations why we sleep, there is still disagreement in this area. The fact that sleep deprivation causes numerous harmful (вредный) effects suggests that the body requires sleep to restore (восстанавливать) itself. However, more research is needed to determine whether this is so or whether sleep is the result of adaptation to the environment. There is also the possibility that these two alternatives may not be incompatible (несовестимый).

Text study

III

Before reading the text on sleep decide whether the following statements are true or false:

1. sleep is a passive state;

2. people breathe slowly and regularly throughout the night;

3. everybody dreams during the night;

4. all sleepers remember their dreams.

Read the text to see whether you were right. Choose the title that best suits it.

1. Two types of sleep.

2. The mystery of sleep.

3. The investigation of sleep.

We may not give it a moment's thought, but most of us will probably spend the third of our lives asleep. Yet the nature of sleep has puzzled mankind for thousands of years; it is only in the last quarter (четверть) of a century that researchers have made scientific attempts to investigate this world, trying to find out why some people have enormous difficulty falling asleep, while others find it impossible to stay awake. Far from being a passive state, sleep is a remarkably active one. While the sleeper is outwardly calm, the electrical activity of the brain never stops. As the sleep becomes deeper and deeper, the brain-waves become larger and more spread out.

While the sleeper still thinks thoughts and moves occasionally, the metabolic processes slow down and the heartbeat drops until deep sleep is reached.

Every day every human being experiences two kinds of sleep that alternate rhythmically throughout the entire sleep period. The discovery of the two kinds of sleep occurred almost accidentally at the University of Chicago. In 1952 Dr. Kleitman became interested in the slow rolling eye movements that accompany sleep onset (начало) and decided to look for these eye movements throughout the night to determine whether they were related to the depth or quality of sleep. An entirely new kind of eye movement was noticed at certain times during night, the eyes began to dart (быстро двигаться) about furiously beneath the closed lids (веки).

Dr. Kleitman coined the term "REM" (for Rapid - Eye -Movement sleep) to define the phenomenon he and his collegues observed. The other kind eventually acquired the name "NREM" sleep. The "NREM" state is often called "quiet sleep", because of the slow, regular breathing, the general absence of body movement, and the slow, regular brain activity shown in the EEG. The body is not paralyzed during NREM sleep. The first sleep of the night is always NREM sleep, which must progress through its various stages before the first REM period occurs. REM sleep, which has been called "active sleep" is an entirely different state of existence. At the onset of REM sleep the sleeper's body is still immobile, but we can see small, convulsive twitches (подергивания) of his face and fingertips (кончики пальцев)

Experts speculate that REM sleep protects us from acting out our dreams and hurting ourselves, and that it is not really sleep at all, but a state in which the subject is awake, but paralyzed and hallucinating. The sleeper's breathing becomes irregular — very fast, then slow — he may even appear to stop breathing for several seconds. If you gently pull back the eyelids the sleeper seems to be actually looking at something. Cerebral blood flow and brain temperature soar to new heights, but large muscles of the body are completely paralyzed: arms, legs, and trunk cannot move.

The NREM-REM cycle varies from 70 to 110 minutes, but averages around 90 min. In the early part of the night sleep is dominated by the NREM state, but as the night progresses, the periods of quiet sleep become shorter and the REM episodes longer. The first REM period lasts 10 min., but by early morning they can last as long as an hour. So we are believed to go into REM sleep and dream roughly every 90 m, all night long. So most of us sleep in two distinct ways: REM sleep, when we dream, and "quiet" sleep when we simply sleep.

XII