一站一坐火柱看世界: 6月 2017

睡眠醫學-輪班工作好傷身!

醫護工作往往需要員工輪班工作(shift work)，以前這種要求令許多人對醫護工作因而卻步。隨著時代改變，現在很多服務性行業員工也需要輪更工作了。所謂輪更工作泛指在傳統工作時間(朝六晚六)以外工作如持續返早、返夜、不定期(早、午、晚)當值等工種。在美國約有29%的工人就需要在朝六晚六以外工作(1)。毫無疑問輪更工作破壞了正常的作息規律(sleep-wake cycle)，因而引起睡眠不足及過度疲勞(2,3)。有研究甚至提出輪更工作可能造成乳癌及冠心病的可能性(4)! 有充份証據顯示睡眠不足引起免疫系統及新陳代謝失調(5)、認知功能受損(6)及容易患上長期病患(7)。

需要輪更工作的員工(Shift Workers, SW) 比較多(risk ratio 1.16,)有睡眠問題的捆擾，以失眠為甚(8)。一般人在當完夜更後在日間較易入睡而且多是熟睡，但他們睡覺的時間通常只會是四至六個小時而已(9)。若果員工的更期太密(兩更相差少於11小時)，他們每次也不會睡得很長(10)。同樣若果員工的更期(早、午、晚)轉得太密(defined as one to three similar shifts in a row)，他們一樣每次也不會睡得很長的。工人經一連串輪班後，他們在第一個休息日(first day off)多能睡八小時以上(11)。他們最常有的問題是嗜睡(excessive sleepiness)，尤其是在清晨或晚上工作(12) 。

當這種因工作輪值制度所引發的作息失調問題(work schedule related sleep/wake Problems)持續達三個月以上，醫學界稱之為輪班工作睡眠紊亂“shift work sleep disorder”(SWD),這是生理節奏睡眠紊亂(clinical circadian rhythm sleep disorder)的一種。粗略估計約10-23%需要輪班工作的人有SWD(12)，而他們比其他員工會更常因嗜睡( excessive sleepiness) 引發意外。

一個函括二百萬人的薈粹分析( systematic review and meta-analysis ) 發現輪更工作(shift work)與心肌梗塞/Myocardial infarction(pooled relative risk 1.23, 95% confidence interval 1.15 to 1.31) and 缺血性中風/ischaemic stroke (1.05,1.01 to 1.09) 有關(13) ，其中以夜更工人有最高風險 (relative risk 1.41)。醫學研究同樣發現輪更工作增加工人變得過重及肥胖的機會(14,15) 。不單如此，更可能導致輪班工人患上糖尿病(adjusted odds ratio 1.12-1.15)(16,17)。

2007年the International Agency for Research on Cancer(IARC) 首先提出輪更工作可能增加工人患上乳癌的風險(18)。但後期的醫學評論卻不認同(19-21) 。亦有醫學評論認為如果員工從事輪更工作超過20年，那麼她們會患上乳癌的風險真的比較高(22-25)。而男士方面，毎從事輪班工作五年就會增加患前列線癌(ca prostate) 的風險2.8%(26)，另外從事輪班工作亦可能令人容易患上腸癌(27)。

大家直覺上都相信從事輪班工作的工人會有較多與工作有關的意外，而事實也是如此(28)，而工人在當夜更工作後翌日揸車亦更容易有意外(29-30) 。

這樣看來輪班工作真的好傷身，然而這種工作模式是全世界的大趨勢，大家未必可以避免，唯有自求多福。

參考文獻:

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