Do bright-light shock exposures during breaks reduce subjective sleepiness in night workers?

Abstract

Night work has many harmful effects on the health, efficiency and safety of workers. This study evaluates the effects of bright-light exposure (BL) on subjective sleepiness during night work. Ninety night workers who have more than a year’s experience at a metallurgy production plant volunteered to participate in this clinical pilot study. Workers were divided into two groups and every group was exposed to either bright light (2500–3000 lux) or normal light (300 lux) during break times at night for two consecutive nights. Fifteen-minute breaks were initiated at 22.00 h (before starting work) 24.00 h, 02.00 h and 04.00 h. The range of subjective sleepiness was assessed by the Stanford Sleepiness Scale (SSS) at 23.00 h, 01.00 h, 03.00 h and 05.00 h. We used SPSS 11.5 for data analysis. The result demonstrated that there were significant differences in the rate of sleepiness between the two groups by paired t-test analysis (P < 0.001). These findings suggest that photic stimulation in industrial settings could increase adaptation to night work.

This is a preview of subscription content, access via your institution.

References

  1. 1

    Nurminen T. Shift work and reproductive health. Scand. J. Work Environ. Health 1998; 24: 28–34.

    PubMed  Google Scholar 

  2. 2

    Folkard S, Lombardi DA, Tucker PT. Shift work: safety, sleepiness and sleep. Ind. Health 2005; 43: 20–3.

    Article  PubMed  Google Scholar 

  3. 3

    Costa G. Shift work and occupational medicine: an overview. Occup. Med. 2003; 53: 83–8.

    Article  Google Scholar 

  4. 4

    Barger LK, Cade BE, Ayas NT et al. Extended work shifts and the risk of motor vehicle crashes among interns. N. Engl. J. Med. 2005; 352: 125–34.

    CAS  Article  PubMed  Google Scholar 

  5. 5

    Beers TM. Flexible schedules and shift work: replacing the ‘9-to-5’ workday? Mon. Labor Rev. 2000; 123: 33–40.

    Google Scholar 

  6. 6

    Shields M. Shift work and health. Health Rep. 2002; 13: 11–33.

    PubMed  Google Scholar 

  7. 7

    Stewart KT, Hayes BC, Eastman CI. Light treatment for NASA shift workers. Chronobiol. Int. 1995; 12: 141–51.

    CAS  Article  PubMed  Google Scholar 

  8. 8

    Dinges DF. An overview of sleepiness and accidents. J. Sleep Res. 2009; 4 (s2): 4–14.

    Article  Google Scholar 

  9. 9

    Eastman CI, Stewart KT, Mahoney MP, Liu L, Fogg LF. Dark goggles and bright light improve circadian rhythm adaptation to night-shift work. Sleep 1994; 17: 535–43.

    CAS  PubMed  Google Scholar 

  10. 10

    Czeisler CA, Allan JS, Strogatz SH et al. Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. Science 1986; 233: 667–71.

    CAS  Article  PubMed  Google Scholar 

  11. 11

    Czeisler CA, Dijk DJ. Use of bright light to treat mal adaptation to night shift work and circadian rhythm sleep disorders. J. Sleep Res. 2009; 4 (s2): 70–3.

    Article  Google Scholar 

  12. 12

    Dijk DJ, Boulos Z, Eastman CI, Lewy AJ, Campbell SS, Terman M. Light treatment for sleep disorders: consensus report: II. Basic properties of circadian physiology and sleep regulation. J. Biol. Rhythms 1995; 10: 113–25.

    CAS  Article  PubMed  Google Scholar 

  13. 13

    Deacon S, Arendt J. Adapting to phase shifts, II. Effects of melatonin and conflicting light treatment. Physiol. Behav. 1996; 59: 675–82.

    CAS  Article  PubMed  Google Scholar 

  14. 14

    Horowitz TS, Cade BE, Wolfe JM, Czeisler CA. Efficacy of bright light and sleep/darkness scheduling in alleviating circadian mal adaptation to night work. Am. J. Physiol. 2001; 281: 384–91.

    Google Scholar 

  15. 15

    Dawson D, Lack L, Morris M. Phase resetting of the human circadian pacemaker with use of a single pulse of bright light. Chronobiol. Int. 1993; 10: 94–102.

    CAS  Article  PubMed  Google Scholar 

  16. 16

    Czeisler CA, Johnson MP, Duffy JF, Brown EN, Ronda JM, Kronauer RE. Exposure to bright light and darkness to treat physiologic maladaption to night work. N. Engl. J. Med. 1990; 322: 1253–9.

    CAS  Article  PubMed  Google Scholar 

  17. 17

    Burgess HJ, Sharkey KM, Eastman CI. Bright light, dark and melatonin can promote circadian adaptation in night shift workers. Sleep Med. Rev. 2002; 6: 407–20.

    Article  PubMed  Google Scholar 

  18. 18

    Mitchell PJ, Hoese EK. Conflicting bright light exposure during night shifts impedes circadian adaptation. J. Biol. Rhythms 1997; 12: 5–15.

    CAS  Article  PubMed  Google Scholar 

  19. 19

    Baehr EK, Fogg LF, Eastman CI. Intermittent bright light and exercise to entrain human circadian rhythms to night work. Am. J. Physiol. Regul. Integr. Comp. Physiol. 1999; 277: 1598–604.

    Google Scholar 

  20. 20

    Campbell SS. Effects of timed bright-light exposure on shift-work adaptation in middle-aged subjects. Sleep 1995; 18: 408–16.

    CAS  PubMed  Google Scholar 

  21. 21

    Koller M, Harma M, Laitinen JT, Kundi M, Piegler B, Haider M. Different patterns of light exposure in relation to melatonin and cortisol rhythms and sleep of night workers. J. Pineal Res. 2007; 16: 127–35.

    Article  Google Scholar 

  22. 22

    Lowden A, Akerstedt T, Wibom R. Suppression of sleepiness and melatonin by bright light exposure during breaks in night work. J. Sleep Res. 2004; 13: 37–44.

    Article  PubMed  Google Scholar 

  23. 23

    Barnes RG, Deacon SJ, Forbes MJ, Arendt J. Adaptation of the 6-sulphatoxymelatonin rhythm in shiftworkers on offshore oil installations during a 2-week 12-h night shift. Neurosci. Lett. 1998; 241: 9–12.

    CAS  Article  PubMed  Google Scholar 

  24. 24

    Dumont M, Benhaberou-Brun D, Paquet J. Profile of 24-h light exposure and circadian phase of melatonin secretion in night workers. J. Biol. Rhythms 2001; 16: 502–11.

    CAS  Article  PubMed  Google Scholar 

  25. 25

    Bjorvatn BR, Kecklund GR, Åkerstedt T. Bright light treatment used for adaptation to night work and re-adaptation back to day life. A field study at an oil platform in the North Sea. J. Sleep Res. 2002; 8: 105–12.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Mohsen Zare.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Karchani, M., Kakooei, H., Yazdi, Z. et al. Do bright-light shock exposures during breaks reduce subjective sleepiness in night workers?. Sleep Biol. Rhythms 9, 95–102 (2011). https://doi.org/10.1111/j.1479-8425.2011.00490.x

Download citation

Key words

  • bright-light exposure
  • shift work
  • sleepiness
  • Stanford Sleepiness Scale