Night shift workers 'at higher risk of DNA damage'

27th June 2017 – Some night shift workers might benefit from a hormone supplement to boost their body's ability to repair DNA damage, according to new research.

A small study published online in the journal Occupational and Environmental Medicine suggests that lower levels of the body clock regulating hormone melatonin found in night workers who sleep in the day might be involved in hindering DNA repair.

Heart attacks, diabetes and cancer

There is mounting evidence that working at night causes poor health. It has been linked to a number of conditions, including a higher risk of heart attack, stroke, diabetes and some cancers.

A research team led by the Fred Hutchinson Cancer Research Center in Seattle has previously demonstrated how day sleepers may be less likely to be able to repair damage to their DNA than those who sleep at night. In 223 shift workers, they found lower levels of a chemical by-product of active DNA tissue repair called 8-OH-dG among the day sleepers.

They said that this made it less likely that the people sleeping during the day would be able to repair cell damage.

Sleep hormone

They concluded that lower levels of the so-called sleep hormone, melatonin, in the day sleepers could be responsible.

Their latest investigation set out to establish whether lower levels of 8-OH-dG might also be caused by working at night. They measured 8-OH-dG levels in the stored urine samples of 50 of the participants in the previous study.

These samples showed that melatonin levels during a night's work were only 20% of those taken when they had a normal night's sleep.

The researchers say that melatonin production boosts the activity of genes that are believed to be vital for repairing DNA damage caused by free radicals that are released during normal cellular activity.

Possible need for supplements

The researchers say that the observational nature of their study means it is not possible to prove cause and effect. Also, participants were mainly white, of similar age, and mostly worked in one profession – healthcare – making it harder to generalise.

However, they conclude: "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."