Book 1 Reading and Speaking (1108795), страница 10
Текст из файла (страница 10)
Infants sleep up to 18 hours per day, andthey spend much more time in deep slow wave sleep. As children mature, they spend less time asleep, and lesstime in deep slow wave sleep. Older adults may sleep only six to seven hours per night, often complain of earlywakening that they cannot avoid, and spend very little time in slow wave sleep.Sleep disordersThe most common sleep disorder, and the one most people are familiar with, is insomnia.
Some people havedifficulty falling asleep initially, but other people fall asleep, and then awaken part way through the night, andcannot fall asleep again. Although there are a variety of short-acting sedatives and sedating antidepressant drugsavailable to help, none of these produces a truly natural and restful sleep state because they tend to suppress thedeeper stages of slow wave sleep.Excessive daytime sleepiness may have many causes. The most common are disorders that disrupt sleepand result in inadequate amounts of sleep, particularly the deeper stages. These are usually diagnosed in the sleeplaboratory. Here, the EEG, eye movements and muscle tone are monitored electrically as the individual sleeps. Inaddition, the heart, breathing, and oxygen content of the blood can be monitored.Obstructive sleep apnea causes the airway muscles in the throat to collapse as sleep deepens.
Thisprevents breathing, which causes arousal, and prevents the sufferer from entering the deeper stages of slow wavesleep. This condition can also cause high blood pressure and may increase the risk of heart attack. There is alsoan increased risk of daytime accident, especially automobile accidents, which may prevent driving. Treatment iscomplex and may include a variety of attempts to reduce airway collapse during sleep. While simple things likelosing weight, avoiding alcohol and sedating drugs prior to sleep, and avoiding sleeping on one’s back cansometimes help, most people with sleep apnea require positive airway pressure to keep the airway open.
This canbe provided by fitting a small mask over the nose that provides an air stream under pressure during sleep. In somecases, surgery is needed to correct the airway anatomy.Periodic limb movements of sleep are intermittent jerks of the legs or arms, which occur as the individualenters slow wave sleep, and can cause arousal from sleep. Other people have episodes in which their muscles failto be paralyzed during REM sleep, and they act out their dreams. This REM behavior disorder can also be verydisruptive to a normal nights’ sleep. Both disorders are more common in people with Parkinson’s disease, and bothcan be treated with drugs that treat Parkinson’s, or with an anti-epileptic drug called clonazepam.Narcolepsy is a relatively uncommon condition (one case per 2,500 people) in which the switchingmechanism for REM sleep does not work properly.
Narcoleptics have sleep attacks during the day, in which theysuddenly fall asleep. This is socially disruptive, as well as dangerous, for example, if they are driving. They tend toenter REM sleep very quickly as well, and may even enter a dreaming state while still awake, a condition known ashypnagogic hallucinations. They also have attacks during which they lose muscle tone, similar to what occursduring REM sleep, but while they are awake. Often, this occurs while they are falling asleep or just waking up, butattacks of paralysis known as cataplexy can be triggered by an emotional experience or even hearing a funny joke.Recently, insights into the mechanism of narcolepsy have given major insights into the processes that controlthese mysterious transitions between waking, slow wave and REM sleep states.
(From Brain Facts: a Primer on theBrain and Nervous System, 2002)Exercise 4. Work in small groups. Write out from the text 15 key word combinations which will help you toretell the text and explain your choice. Then together agree on the final list of word combinations.Exercise 5. In the following text the paragraphs are mixed. Put them in the correct logical order.
The firstand the last paragraphs are in their right places.How long can humans stay awake?J. Christian Gillin, a professor of psychiatry at the University of California, San Diego, conducts research onsleep, chronobiology and mood disorders. He supplies the following answer.(А) The easy experimental answer to this question is 264 hours (about 11 days). In 1965, Randy Gardner, a17-year-old high school student, set this apparent world-record for a science fair. Several other normal researchsubjects have remained awake for 8 to 10 days in carefully monitored experiments.
None of these individualsexperienced serious medical, neurological, physiological or psychiatric problems. On the other hand, all of themshowed progressive and significant deficits in concentration, motivation, perception and other higher mentalprocesses as the duration of sleep deprivation increased. Nevertheless, all experimental subjects recovered torelative normality within one or two nights of recovery sleep. Other anecdotal reports describe soldiers stayingawake for four days in battle, or unmedicated patients with mania going without sleep for three to four days.(B) The more difficult answer to this question revolves around the definition of "awake." As mentioned above,prolonged sleep deprivation in normal subjects induces altered states of consciousness (often described as"microsleep"), numerous brief episodes of overwhelming sleep, and loss of cognitive and motor functions.
We all26know about the dangerous, drowsy driver, and we have heard about sleep-deprived British pilots who crashed theirplanes (having fallen asleep) while flying home from the war zone during World War II. Randy Gardner was"awake" but basically cognitively dysfunctional at the end of his ordeal.(C) In the case of rats, however, continuous sleep deprivation for about two weeks or more inevitably causeddeath in experiments conducted in Allan Rechtschaffen’s sleep laboratory at the University of Chicago. Twoanimals lived on a rotating disc over a pool of water, separated by a fixed wall. Brainwaves were recordedcontinuously into a computer program that almost instantaneously recognized the onset of sleep. When theexperimental rat fell asleep, the disc was rotated to keep it awake by bumping it against the wall and threatening topush the animal into the water.
Control rats could sleep when the experimental rat was awake but were movedequally whenever the experimental rat started to sleep. The cause of death was not proven but was associated withwhole body hypermetabolism.(D) In certain rare human medical disorders, the question of how long people can remain awake raises othersurprising answers, and more questions. Morvan’s fibrillary chorea or Morvan’s syndrome is characterized bymuscle twitching, pain, excessive sweating, weight loss, periodic hallucinations, and severe loss of sleep(agrypnia).
Michel Jouvet and his colleagues in Lyon, France, studied a 27-year-old man with this disorder andfound he had virtually no sleep over a period of several months. During that time he did not feel sleepy or tired anddid not show any disorders of mood, memory, or anxiety. Nevertheless, nearly every night between 9:00 and 11:00p.m., he experienced a 20 to 60-minute period of auditory, visual, olfactory, and somesthetic (sense of touch)hallucinations, as well as pain and vasoconstriction in his fingers and toes.
In recent investigations, Morvan’sSyndrome has been attributed to serum antibodies directed against specific potassium (K+) channels in cell andnerve membranes.(E) Another rare disorder, Fatal Familial Insomnia (FFI), is an autosomal dominate disease that is invariablyfatal after about six to 30 months without sleep. FFI is probably misnamed because death results from multipleorgan failure rather than sleep deprivation. The pathological processes include degeneration of the thalamus andother brain areas, over-activity of the sympathetic nervous system, hypertension, fever, tremors, stupor, weightloss, and disruption of the body's endocrine systems. FFI belongs to a class of infectious prion diseases thatinclude Mad Cow Disease.(F) To return to the original question, "How long can humans stay awake?" the ultimate answer remainsunclear. Despite the rat studies in Chicago, I am unaware of any reports that sleep deprivation per se has killed anyhuman (excluding accidents and so forth).
Indeed, the U.S. Department of Defense has offered research fundingfor the goal of sustaining a fully awake, fully functional "24/7" soldier, sailor, or airman. Future warriors will faceintense, around-the-clock fighting for weeks at a time. Will bioengineering eventually produce genetically-clonedsoldiers and citizens with a variant of Morvan’s syndrome who need no sleep but remain effective and happy? Ihope not. A good night’s sleep is one of life’s blessings.
As Coleridge wrote years ago, "Oh sleep! It is a gentlething, beloved from pole to pole," and Wilse Webb, a prominent sleep researcher, more recently called sleep thegentle tyrant: It can be delayed but not defeated.Exercise 6. Are the following statements true or false, according to the text? Explain your answer.1. A healthy person can survive without sleep no more than three days.2.
Sleep deprivation damages normal functioning of the organism.3. Prolonged sleep deprivation produces no negative effect on health.4. Sleep disorders may be a symptom of serious diseases.5. Sleep disorders can be inherited.6. Research of sleep has serious implications for economy and industry.Exercise 7. Would you like to be able to live without sleep? Why? Why not?Exercise 8. Summarize everything you know about sleep, its functions and sleep disorders into one report.27Unit 8. CoffeeIn the cauldron boil and bake;Eye of newt and toe of frog,Wool of bat and tongue of dog,Adder’s fork and blind-worm’s sting,Lizard’s leg and howlet’s wing.
. .William Shakespeare, MacbethExercise 1. What do you know about coffee?1. What is coffee produced from?2. In what regions of the world is coffee grown?3. What do you know about coffee plants?4. What is the main active ingredient of coffee?5. How does caffeine affect the human body?6. What are the risks of coffee overdose?7. What other products contain caffeine?8. How is the effect of coffee different from the effect of tea if caffeine is contained in both?Exercise 2. Read the following facts about caffeine and coffee trees to check your answers in Exercise 1.What is caffeine? An alkaloid found in coffee, cocoa beans, tea, kola nuts and guarana. Also added tomany fizzy drinks, energy drinks, pep pills and cold and flu remedies.
For a single portion of espresso, 50 to 55roasted coffee beans are required; a single imperfect bean will taint the whole sufficiently to be noticeable. This isbecause human olfaction and taste senses originated as defense mechanisms that protected our ancestors fromrotten—hence, unhealthy—foods.What does caffeine do? A stimulant of the central nervous system. Pure caffeine is a moderately powerfuldrug and is sometimes passed off as amphetamine. In small doses, such as the 150 milligrams in a typical cup offilter coffee, it increases alertness and promotes wakefulness. Caffeine also raises heart and respiration rate andpromotes urine production.
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