Night shift work heightens cancer risk

Night shift work has been found to cause circadian rhythm disruptions and can alter the expression of tumour-related genes, making one more vulnerable to the DNA damage that leads to cancer. According to Hans Van Dongen, Director of Washington State University’s (WSU) Sleep and Performance Research Center, night shift workers face “considerable” health disparities – several years of experimental and observational research has also confidently shown night shift workers face an increased risk of several cancers, as well as mental health disorders.

A team at WSU sought to address how night shift work elevates cancer risk by recruiting 14 healthy US volunteers for a comprehensive seven-day laboratory study.

In the sleep lab at WSU, half the subjects completed a 72-hour simulated day shift routine while the other half completed a simulated night shift routine. After the simulation, the participants completed a constant routine protocol in which they were kept awake for 24 hours under consistent light exposure. This part of the protocol is designed to allow investigation of biological rhythms independent of external influences.

The researchers noticed how the night shift routine significantly altered the normal circadian rhythmicity of genes involved in cancer hallmark pathways. They suggest that not only are the expression of certain cancer-related genes directly altered by disrupting circadian rhythms, but night shift schedules seem to negatively influence the body’s natural DNA repair processes

Investigating white blood cells from the participants in in-vivo experiments later on, the researchers discovered those cells from the night shift group were much more vulnerable to radiation-induced DNA damage.

“Taken together, these findings suggest that night shift schedules throw off the timing of expression of cancer-related genes in a way that reduces the effectiveness of the body’s DNA repair processes when they are most needed,” explained Jason McDermott, a computational scientist with the Pacific Northwest National Laboratory’s Biological Sciences Division.

The researchers will soon investigate real-life night shift workers to see if these findings translate to those who have had circadian disruptions for several years, as it is possible for some people’s systems to adapt to long-term nightshift work and mitigate the acute changes seen in the short-term study.

Read: Higher risk of cancer when indulging in late night meals

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Category: Features, Health alert