A new study published in the journal Anaesthesia, has found the mechanism that underlies the health effects of working night shifts: night work with little sleep can damage a person’s DNA, thus increasing their long-term risk of cancer, and other cardiovascular, metabolic and neurodegenerative diseases.
Although it is clear from the study that acute sleep deprivation while working nights can have harmful effects on one’s health, it’s not clear whether catching up on sleep during the day mitigates them.
The Hong Kong-based study may also hold implications in a place like India where laws have changed to expand the nighttime workforce; sectors like IT and media are starting to allow women to work a certain number of hours in the night, given certain conditions, whereas before, night shifts were limited to men only. The study may now also counterbalance the hitherto aspirational quality of jobs in call centers, IT businesses, or even media — industries known to demand working nights.
Researchers said that earlier studies have always highlighted the detrimental health effects of working at night, but not the mechanisms through which acute sleep deprivation leads to chronic diseases. This study examined the relationship between acute sleep deprivation on DNA damage. “Although this work is very preliminary, it is clear from the results that even a single night of sleep deprivation can trigger events that may contribute to the development of chronic disease,” one of the researchers Siu-Wai Choi, of the University of Hong Kong, said.
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For the study, researchers observed two groups: one comprising 24 doctors, who had been working five to six overnight shifts per month, and getting just two to four hours of sleep a night; and the other group included 25 clinicians, who were not required to work overnight and managed a minimum of six hours of sleep a night.
Through blood samples, researchers found that the doctors who worked nights demonstrated more breaks in genetic material, and a corresponding decrease in capacity for DNA repair. More specifically, doctors who were required to work overnight demonstrated 30% higher DNA breaks, as compared with those doctors not required to work overnight; this DNA damage increased by more than 25%after a single night of acute sleep deprivation.
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DNA damage is a change in the basic structure of genetic material that is maintained and replicated into new cells. Double‐strand breaks are particularly hazardous, as repair failure causes cell death that causes cancer, gives rise to other autoimmune conditions, and neurodegeneration. Partially- or shoddily-repaired DNA can lead to cancer causing genetic mutations.
The study also showed that the expression, or activity, of the gene that controls DNA repair is less among night workers, which further decreases after acute sleep deprivation, helping to explain why night workers showed impaired DNA repair.
