DNA and the Night Shift

A new study has found that night shift work is associated with diminished ability to repair DNA. The connection between suppressed melatonin levels and DNA repair is just another example of the harmful effects of blue light at night.

26 June 2017

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.

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 tumours.

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.

Now US researchers have discovered that when people work nights they produce 80 per cent 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.

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.

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.’

“Over time, this accumulation would likely increase the risk of cancer across multiple sites as has been observed among shift workers,” she added.

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 per cent.

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.

“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.

The research was published in the journal Occupational & Environmental Medicine.


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