高级综合英语教程1

Unit 4

I. Background to Text 1

Sleep is a state of reduced awareness and activity that occurs at regular intervals in most mammals and birds, though there is considerable variation in the amount of time spent sleeping. Sleep differs from hibernation in that it occurs daily rather than seasonally, and involves less drastic reductions in metabolism. The function of sleep is unclear. People deprived of sleep become irritable, uncoordinated, forgetful, hallucinatory, and even psychotic.

In humans, sleep is linked with hormone levels and specific brain electrical activity, including delta waves, quite different from the brain’s waking activity.

REM (rapid eye movement) phases, associated with dreams, occur at regular intervals during sleep, when the eyes move rapidly below closed lids. In some species sleep may make animals inconspicuous at times when they might be vulnerable to predators.

Research on sleep has been going on for years to find the following questions: Why humans of different ages need different length of time sleeping? How long does a human really need to sleep without negative effect? Why can some people cope with fairly little sleep whereas others seem never to have enough sleep? Is it necessary to have a little sleep during the day? Can one change his/her patterns of sleep? What is the relationship between sleep and dream? To find answers to such questions, scientists have conducted a great variety of experiments. The texts chosen for this unit describe some of the findings.

II. Detailed study of the text

1. optimum (L.2) adj.: the best and most favourable, e.g. optimum environment for

that rare species of animal

2. compensate for (L.11): make up for (the disadvantage, loss, etc.)

3. highlight (L.13) vt.: draw attention to; emphasise

4. …as this is the time that the body’s natural rhythms dip. (L.22)

…as in the afternoon, the body’s physiological movement drops below the normal level.

dip vi.: drop below the surface or level; slope downwards

5. anticipate (L.25) vt.: expect; look forward to

6. If we have seven hours’ sleep and still feel dreadful, it is probably because of

the quality of our sleep rather than the quantity. (L.28)

If we have slept for seven hours but still feel very sleepy or tired, it may not be that the time for sleep is not long enough but that the sleep is not sound and peaceful.

7. “There is a natural distribution of good and poor sleepers, in the same way

that there is a variation in height,”… (L.30)

Just as there are tall persons and short ones, so there are naturally good sleepers