Sleep
We all know that the normal human daily cycle of activity is of some 7-8 hour’s sleep alternating with some 16-17 hours' wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified.
The question is no mere academic one. The case, for example, with which people can change from working in the day to working at night, is a question of growing importance in industry where automation calls insistently for round-the-clock working of machines. It normally takes from five days to one week for a person to adapt to a reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12 midnight to 8 a. m. one week, 8 am to 4 pm the next, and 4 pm to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently.
One answer would seem to be longer periods on each shift, a month, or even three months. Recent research by Bonjer of the Netherlands, however, has shown that people on such systems will revert to their normal habits of sleep and wakefulness during the week-end and the this is quite enough to destroy any adaptation to night work built up during the week.
The only real solution appears to be to hand over the night shift to a corps of permanent night workers whose nocturnal wakefulness may persist through all weekends and holidays. An interesting study of the domestic life and health of night-shift workers was carried out by Brown. She found a high incidence of disturbed sleep, digestive disorder and domestic disruption among those on alternating day and night shifts, but no abnormal occurrence of these symptoms among those on permanent night work.
1. The question raised in Paragraph 2 is “no mere academic one” .
A. because Bonjer’s findings are different from Brown's.
B. because sleep normally coincides with the hours of darkness.
C. because some people can change their sleeping habits easily.
D. because shift work in industry requires people to change their sleeping habits.
2. According to the passage, the main problem about night work is that
A. people hate the inconvenience of working on night shifts.
B. your life is disturbed by changing from day to night routines and back.
C. not all industries work at the same hours.
D. it is difficult to find a corps of good night workers.
3. According to the passage, the best solution to the problem seems to be
A. not to change shifts from one week to the next.
B. to make periods on each shift longer.
C. to employ people who will always work at night.
D. to find ways of selecting people who adapt quickly.
4. In the second paragraph, “the third” means
A. the third week.
B. the third shift.
C. a third of the time.
D. the third routine.
5. In the last sentence of the second paragraph, “another” means
A. another routine.
B. another shift.
C. another week.
D. another person.
上一页 [1] [2]
责任编辑：wangpeng6151
