Working night shifts may damage DNA, study suggests

A new study suggests that people who work the night shift put their body at risk of DNA damage.

This is so because the body might have less capacity to repair everyday damage suffered by cells, according to the researchers.

Parveen Bhatti, lead researcher, explained that a chemical, 8-OH-dG, is excreted in the urine when the body repairs DNA damage that occurs during normal body processes.

“So we think lower clearance [of 8-OH-dG] likely reflects a reduced ability to repair DNA damage. Over time, such DNA damage might contribute to cancer or other diseases.”

He said the whole process might be due to insufficient levels of melatonin, a hormone that helps regulate the body’s internal clock, adding that night shift workers tend to have lower melatonin levels when compared to people who work during the day.

The findings, which was published on June 26 in the Occupational & Environmental Medicine journal, are based on 50 men and women who worked the night shift in health care jobs.

Overall, the workers were found to have lower levels of 8-OH-dG in their urine when they worked at night as against nights where they were able to sleep.

Bhatti said the results support an earlier study in which his team followed 223 workers, including the 50 in this one. There, researchers found that workers’ 8-OH-dG levels were lower during daytime sleep, versus nighttime sleep.

The researchers also saw evidence that lower melatonin levels correlated with lower 8-OH-dG. The 50 workers in the latest study were those showed the biggest drop in melatonin during night work versus night sleep.

Although he admits that the results do not prove it, Bhatti said he thinks melatonin is responsible.

“I’d like to do a trial where we give melatonin to shift workers with low melatonin levels, then see if it affects this biomarker,” Bhatti said, referring to 8-OH-dG.

However, until more research is done, he doesn’t suggest that shift workers use melatonin supplements in hopes of preventing DNA damage.

He advised night shift workers to be extra vigilant about maintaining a healthy lifestyle, eating a balanced diet, getting regular exercise and to avoid smoking.

The research was carried out by researchers from the Fred Hutchinson Cancer Research Centre, Seattle, US.