Night shift not the right shift for a healthy body

Night shift work may stop the body repairing the 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 the disruption to the body's natural body clock was responsible for the increased risk of chronic illness, but could not pinpoint the mechanism.

Now US researchers have discovered people who work at night produce 80% less of the chemical that is a by-product of DNA tissue repair. This indicates the body is not carrying out the crucial restoration to cells. They believe the effect could be caused by a lack of melatonin, the sleep hormone.

Parveen Bhatti, of the Fred Hutchinson Cancer Research Centre in Seattle, Washington, 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 said.

The study tested 50 night-shift workers for levels of 8-OH-dG - a chemical produced when DNA is repaired. They tested them again when they were working days and found levels jumped by 300%.

They believe shift workers may need to take sleep hormone supplements to allow DNA to carry out repairs as they sleep in the day.

"Melatonin supplementation should be explored as an intervention to reduce the occurrence of potentially carcinogenic DNA damage among shift workers," she said.

The research was published in Occupational & Environmental Medicine. - The Daily Telegraph

• This article was originally published in The Times.