Oxidative DNA damage during sleep periods among nightshift workers

Abstract

Reduced excretion of 8-OH-dG among nightshift workers during day sleep may reflect reduced functioning of DNA repair machinery, which could potentially lead to increased cellular levels of oxidative DNA damage. Melatonin disruption among nightshift workers may be responsible for the observed effect, as melatonin is known to enhance repair of oxidative DNA damage. Quality of sleep may similarly impact DNA repair. Cellular levels of DNA damage will need to be evaluated in future studies to help interpret these findings.

Oxidative DNA damage during night shift work

“…We recently reported decreased urinary excretion of 8-hydroxygeoxyguanosine (8-OH-dG), the most common and mutagenic DNA lesion induced by reactive oxygen species,1 during day sleep among shift workers as compared with night sleep on their first day off from work 2. Our analyses suggested that this effect was driven by a lack of melatonin during day sleep relative to night sleep.…”

“…For our recent study evaluating day sleep versus night sleep differences in 8-OH-dG excretion, we selected 223 female and male shift workers from the healthcare industry in Seattle with existing data and urine samples from two previous studies of shift work 2. Shift work was defined as working at least 20 hours/week and 8 hours/shift with each shift ending no earlier than  06:00.…”

“…Shift work was defined as working at least 20 hours/week and 8 hours/shift with each shift ending no earlier than  06:00. Among other eligibility criteria,2 participants could not be taking melatonin supplements. Urine samples were available for all 223 shift workers, but we only had resources available to select 50 participants for inclusion in the current study.…”

“…Research interviewers previously measured body mass index (BMI) and collected information about physical activity 2. During the sleep periods over which urine was collected (see below), subjects wore an actigraph (Actiwatch-16, Mini Mitter, Bend, Oregon, USA) to measure sleep quality 2…”

“…To determine if similar effects of melatonin suppression occur during night work, we obtained new measures of 8-OH-dG in night work urine samples from a subset of the shift workers included in our previous analysis 2. If excretion of 8-OH-dG during night work among these subjects is also decreased relative to night sleep, it would provide additional support for our hypothesis that reduced melatonin among shift workers is associated with decreased oxidative DNA damage repair capacity.…”