We all know that the normal human daily cycle of activity1 is of some 7-8 hours' sleep alternating with some 16-17 hours' wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness2. Our present concern is with how easily and to what extent this cycle can be modified.

　　The question is no mere academic one.3 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 am 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 another4，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 weekend5 and that 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 workers6 whose nocturnal wakefulness7 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.

　　詞匯：

　　alternate /'oiltsneit/ vL 交替，輪換 wakefulness /'weikfulnis/ n.醒著，不睡 coincide /^suin'said/ vL 同時(shí)發(fā)生;一致, 相符

　　modify /'mDdifai/ vt改變，修改，修飾;緩 和，減輕

　　automation /lOit^'meiJsn/ n.自動(dòng)化 insistently /in'sistsntli/ adv.堅(jiān)持地，執(zhí)拗

　　地;迫切地，急切地 reverse /n丨V3:s/ vt.使顛倒,使倒轉(zhuǎn) routine /rui'tiin/ n.常規(guī)，例行公事 revert /ri丨V3it/ vL 恢復(fù)，回復(fù)corps /ko:(r)/ n.共同.;!：作或活動(dòng)的一群 人;特種部隊(duì)，特殊軍種 permanent / 丨p3im3n3nt/ adj.永久的，持久的 nocturnal /nok'tsinl/ adj.夜間發(fā)生的，夜間 活動(dòng)的

　　incidence /丨insidsns/ n.發(fā)生(率) digestive /difd3estiv，dai-/ adj.消化的，助 消化的

　　disruption /dis'rAppn/ n.混亂，分裂，崩演 abnormal /aeb'noiml/ adj.反常的，變態(tài)的 occurrence /s'kArsns/ n.發(fā)生，出現(xiàn);(偶發(fā)

　　‘性)事件

　　symptom /'simptam/ n.表征，征病征， 癥狀

　　注釋：

　　1. the normal human daily cycle of activity ：人們每天正�；顒�(dòng)的周期

　　2. the sleep normally coincides with the hours of darkness:睡目民通常與黑夜時(shí)間重疊

　　3. The question is no mere academic one.這不僅僅是一個(gè)簡(jiǎn)單的學(xué)術(shù)問題。，

　　4. This means that no sooner has he got used to one routine than he has to change to another：這就 意味著丨他剛剛習(xí)慣了一種方式又不得不改為另一種。此句中的no sooner... than...是倒 裝結(jié)構(gòu)。no sooner +主語(yǔ)助動(dòng)詞倒裝結(jié)構(gòu)(has he...)的意思是“一……就……”。如:1 had no sooner reached home than it began to rain.我剛到家天就下雨了�？梢钥闯觯�只有當(dāng) no sooner放在句首位置時(shí)，“主語(yǔ)-助動(dòng)詞”這一序列才發(fā)生變化。

　　5. people on such systems will revert to their normal habits of sleep and wakefulness during the weekend:在周末，按照這些體制工作的人會(huì)恢復(fù)他們通常的睡眠和清醒的習(xí)慣。

　　6. a corps of permanent night workers:—隊(duì)長(zhǎng)期上晚班的工人

　　7. nocturnal wakefulness ：夜間不眠