A number of studies have linked working night shifts to a raised risk of cancer — possibly because it disrupts the circadian rhythm, or ‘body clock’, which has a knock-on effect on genes.
However, new research bythe University of Oxford suggests that night work actually has ‘little or no effect’ on breast cancer risk.
The thinking has been that people who work at night don’t produce enough melatonin, a hormone that helps to prevent tumour formation (this is because the body mostly produces melatonin at night and levels drop in the presence of light).
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But analysis of studies involving more than 800,000 women showed the incidence of breast cancer was the same whether they had worked night shifts for decades or had never worked one.
Daily Mail