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Night shifts can damage DNA repair

Night shifts can damage DNA repair

Night work is related to reduced DNA damage recovery

Αs showed by an observation study in healthcare workers, suggesting that this effect is driven by the suppression of melatonin.


The study investigated a subgroup of shift-shift workers, who were taken from a previous study of 223 shift workers, which showed that daytime sleep is associated with reduced excretion of in the urine, a common mutagenic DNA damage caused by active oxygen species.


Low levels suggest the reduced capacity of repair mechanisms that would usually remove 8-OH-dG by excretion, which appears to be driven by a lack of circulating melatonin during daytime sleep.


Circulating melatonin levels were much lower when the shift workers worked at night (median of 17.1 ng / mg creatinine) than when sleeping at night (median 51.7 ng / mg creatinine).

Average sleep duration during the day was 5.5 hours, compared with 7.5 hours when shift workers slept at night.


The results show that, compared to nighttime sleep, reduced melatonin production among shifts during night work is associated with significantly reduced excretion of 8-OH-dG in the urine, Fred researchers reported Hutchinson Cancer Research Center in Seattle, USA.


The researchers concluded:

"If these results are confirmed, melatonin supplementation should be seen as an intervention to reduce the likelihood of carcinogenic damage to DNA in shift workers"


  1. Bhatti P, Mirick DK, Randolph TW, et al. Oxidative DNA damage during night shift work. Occup Environ Med2017. doi:10.1136/oemed-2017-104414.
  2. Bhatti P, Mirick DK, Randolph TW, et al. Oxidative DNA damage during sleep periods among nightshift workers. Occup Environ Med2016;73:537-44. doi:10.1136/oemed-2016-103629pmid:27307003.
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