【英语翻译Weallknowthatthenormalhumandailycycleofsome7-8hours'sleepalternatingwithsome16-17hours'wakefulnessandthat,broadlyspeaking,thesleepnormallycoincideswiththehoursofdarkness.Ourpresentconcerniswinhoweasily】

　　英语翻译

　　Weallknowthatthenormalhumandailycycleofsome7-8hours'sleepalternatingwithsome16-17hours'wakefulnessandthat,broadlyspeaking,thesleepnormallycoincideswiththehoursofdarkness.Ourpresentconcerniswinhoweasilyandtowhatextentthiscyclecanbemodified.

　　Thequestionisnomoreacademicone.Thecase,forexample,withwhichpeoplecanchangefromworkinginthedaytoworkingatnightisaquestionofgrowingimportanceindustrywhereautomationcallsinsistentlyforround-the-clockworkingofmachines.Itnormallytakesfromfivedaystooneweekforapersontoadapttoareversedofsleepandwakefulness,sleepingduringthedayandworkingatnight.Unfortunatelyitisoftenthecaseinindustrythatshiftsarechangedeveryweek;apersonmayworkfrom12midnightto8a.m.oneweek,8a.m.to4p.m.thenext,and4p.m.to12midnightthethirdandsoon.Thismeansthatnosoonerhashegotusedtooneroutinethanhehastochangetoanother,sothatmuchofhistimeisspentneitherworkingnorsleepingveryefficiently.

　　Oneanswerwouldseemtobelongerperiodsoneachshift,amonth,oreventhreemonths.RecentresearchbyBonjeroftheNetherlands,however,hasshowsthatpeopleonsuchsystemswillreverttotheirnormalhabitsofsleepandwakefulnessduringtheweek-endandthatthisisquiteenoughtodestroyanyadaptationtonightworkbuiltupduringtheweek.

　　Shefoundahighincidenceofdisturbedsleep,digestivedisorderanddomesticdisruptionamongthoseonalternatingdayandnightshifts,butnoabnormaloccurrenceofthesesymptomsamongthoseonpermanentnightwork.