Night shift work may stop the body repairing daily damage to DNA and raise the risk of mutations which lead to cancer, a new study suggests.一项新研究显示，上夜班会阻止身体修复日常的DNA损伤，令基因突变风险增大进而引发癌症。
The link between working at night and poor health has been known for several years, with those who work after dark more likely to suffer diabetes, obesity, poor fertility, heart attacks and tumors.人们多年前就已经知道上夜班和健康不良之间的联系。那些上夜班的人更容易患上糖尿病、肥胖、生育困难、心脏病和肿瘤。
Scientists believed that disruption to the body’s natural body clock was responsible for the increased risk of chronic illness, but could never pinpoint the mechanism.科学家认为，扰乱人体自然的生物钟会增加慢性病的风险，但却无法确定其原理。
Now US researchers have discovered that when people work nights they produce 80 percent less of a chemical which is a by-product of DNA tissue repair. They say it indicates that the body is not carrying out the crucial restoration to cells which should happen naturally overnight.如今美国研究人员发现，人们上夜班时，体内分泌的一种化学物质将减少80%，这种化学物质是修复DNA组织的副产品。研究人员称，这表明人体没有对受损的细胞进行关键的修复，这种修复本应在夜间自然地完成。
They believe the effect could be caused by a lack of melatonin, the sleep hormone, which is far lower among people who sleep in the daytime.科学家认为，这种效应可能是由褪黑激素（睡眠荷尔蒙）的缺乏引发的，在白天睡觉的人群当中，这种激素水平要低得多。
Dr Parveen Bhatti, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA, said if awake at night the body has ‘reduced capacity to repair and clear oxidative DNA damage.’美国华盛顿州西雅图的福瑞德哈金森肿瘤研究中心的帕尔文•巴提博士说，如果夜里醒着，身体就会“降低修复和清除DNA氧化损伤的能力。”
“Over time, this accumulation would likely increase the risk of cancer across multiple sites as has been observed among shift workers,” she added.她补充道：“长此以往，累积的损伤就会增加身体多处的癌症风险，这些都是在倒班工人身上观察到的。”
The study tested 50 night shift workers for levels of 8-OH-dG - a chemical which is produced when DNA is repaired. They then tested them again when they were working days, and found levels jumped by 300 percent.该研究检测了50个夜班工人体内的8-OH-dG——人体修复DNA损伤时产生的化学物质。然后研究人员又在这些工人上白班时给他们做了检测，发现这种化学物质的分泌量增加了300%。
They believe that shift workers may need to take sleep hormone supplements to allow DNA to carry out repairs as they sleep in the day.科学家认为，倒班工人也许需要摄入睡眠荷尔蒙补充剂，让他们在白天睡觉时DNA也可以正常地自我修复。
“If such effects are confirmed, melatonin supplementation should be explored as an intervention to reduce the occurrence of potentially carcinogenic DNA damage among shift workers,” added Dr Bhatti.巴提博士补充道：“如果效果得到证实，应该探讨用褪黑激素补充剂进行干预，来减少倒班工人具有潜在致癌性的DNA损伤。”
The research was published in the journal Occupational & Environmental Medicine.该研究报告发表在《职业与环境医学》杂志上。 
