Original Article

International Archives of Occupational and Environmental Health

, Volume 86, Issue 8, pp 923-930

Open Access This content is freely available online to anyone, anywhere at any time.

Relationship between intensity of night shift work and antioxidant status in blood of nurses

  • Jolanta GromadzińskaAffiliated withNofer Institute of Occupational Medicine Email author 
  • , Beata PeplonskaAffiliated withNofer Institute of Occupational Medicine
  • , Wojciech SobalaAffiliated withNofer Institute of Occupational Medicine
  • , Edyta ReszkaAffiliated withNofer Institute of Occupational Medicine
  • , Wojciech WasowiczAffiliated withNofer Institute of Occupational Medicine
  • , Agnieszka BukowskaAffiliated withNofer Institute of Occupational Medicine
  • , Jenny-Anne LieAffiliated withInstitute of Occupational Health

Abstract

Purpose

Light-at-night exposure can disrupt the human circadian rhythm via clock gene expressions. The circadian rhythm influences antioxidant enzymes’ activity and cellular mRNA levels of these enzymes. The employees working based on a shift system adjust to the changes occurring both on the cell level and on the level of the whole organism. Therefore, a question should be answered whether shift work disturbs oxidant–antioxidant balance and/or generates oxidative stress.

Methods

A cross-sectional study was conducted among nurses selected from the Local Registry of the Chamber of Nurses and Midwives in Lodz: 359 nurses worked daily only and 349 working rotating night shifts. These two groups differed significantly in respect of age (p < 0.0001), menopausal status (p < 0.0001), and current smoking habit (p = 0.02). The average total work duration was significantly shorter (12.4 years) in nurses working currently rotating night shifts who worked significantly longer on night shifts than day-workers (26.6 years).

Results

We found statistically significant higher red blood cell glutathione peroxidase in nurses working on night shifts (21.0 ± 4.6 vs. 20.0 ± 5.0 U/g Hb, p < 0.009) after adjusting for age, oral contraceptive hormone use, smoking, and drinking alcohol during last 24 h. Statistically significant lower vitamin A and E levels were found in the premenopausal women working in rotating system (0.690 ± 0.238 vs. 0.786 ± 0.262 μg/ml, p < 0.0001 for vitamin A and 10.93 ± 4.15 vs. 12.78 ± 4.75 μg/ml, p < 0.0001 for vitamin E). The marker of lipid peroxidation (TBARS concentration) was significantly lower in the premenopausal nurses than postmenopausal ones working day shifts only (2.06 ± 0.76 vs. 2.21 ± 0.80 nmol/ml, p < 0.038). We observed that erythrocyte GSH-Px activity rose statistically significant in nurses working more night shifts per month (p < 0.01).

Conclusions

The results quoted above seem to support the existence of an association between light-at-night exposure and blood glutathione peroxidase activity in female shift workers. Nevertheless, in order to explain the mechanisms of this association, we need more studies.

Keywords

Antioxidants TBARS Night shift work Selenium Light-at-night exposure