The Change of Sleep Quality after Transition to Consecutive Day Shift from Day and Night Shift: A Motor Assembly Factory Case

주야2교대제에서 주간연속2교대제로의 전환 후 수면의 질 변화 : 일개 완성차 제조사의 사례

Song, Hansoo

  • Received : 2015.12.07
  • Accepted : 2015.12.21
  • Published : 2015.12.31


Objectives: The major objective of this study was to analyze insomnia after the change to consecutive day shift from day and night shift in a motor assembly factory. Materials: Data were collected at before and after shift system change through a survey conducted by a labor union. We analyzed transition of PSQI(Pittsburgh Sleep Quality Index) among 222 workers by separating the day shift week and night shift week. The cut-off point of insomnia was 8.5 on the PSQI. Results: Mean PSQI in the day shift week significantly did not decrease, going from $6.36{\pm}3.23$ to $6.46{\pm}3.00$(p=0.612 by paired t-test), Mean PSQI for night shift week significantly decreased from $8.31{\pm}3.36$ to $6.19{\pm}3.18$(p<0.001 by paired t-test). However, mean PSQI in the day shift week increased from $6.33{\pm}3.83$ to $7.11{\pm}2.86$ in ${\geq}50$ years(p=0.085, by repeated measured ANOVA). Mean PSQI score in the night shift week improved more in the married group(from $8.38{\pm}3.27$ to $6.12{\pm}3.18$) than in the non-married group(from $7.82{\pm}3.27$ to $6.12{\pm}3.18$)(p=0.038, by repeated measured ANOVA). Conclusions: The change to consecutive day shift improved insomnia in night shift. However, insomnia in the day shift week was worsened among those more than 50 years old.


shift work;insomnia;PSQI


  1. Akerstedt T. Shift work and disturbed sleep/wakefulness. Occup Med(Lond) 2003;53(2):89-94
  2. Bannai A, Tamakoshi A. The association between long working hours and health: A systematic review of epidemiological evidence. Scand J Work Environ Health 2014;40(1):5-18
  3. Barger LK, Cade BE, Ayas NT, Cronin JW, Rosner B et al. Extended work shifts and the risk of motor vehicle crashes among interns. N Engl J Med 2005;352(2): 125-134
  4. Boivin DB, Boudreau P. Impacts of shift work on sleep and circadian rhythms. Pathol Biol(Paris) 2014;62(5): 292-301
  5. Cho YW, Shin WC, Yun CH, Hong SB, Kim JH et al. Epidemiology of insomnia in Korean adults: prevalence and associated factors. J Clin Neurol 2009;5(1):20-23
  6. Cho YW, Lee JH, Son HK, Lee SH, Shin C et al. The reliability and validity of the Korean version of the Epworth sleepiness scale. Sleep Breath 2011 ;15(3):377-384
  7. Dembe AE, Erickson JB, Delbos RG, Banks SM. The impact of overtime and long work hours on occupational injuries and illnesses: new evidence from the United States. Occup Environ Med 2005;62:588-59
  8. Drake CL, Roehrs T, Richardson G, Walsh JK, Roth T. Shift work sleep disorder: prevalence and consequences beyond that of symptomatic day workers. Sleep 2004;27(8):1453-1462
  9. Gumenyuk V, Roth T, Drake CL. Circadian phase, sleepiness, and light exposure assessment in night workers with and without shift work disorder. Chronobiol Int 2012;29(7):928-936
  10. Guo Y, Liu Y, Huang X, Rong Y, He M et al. The effects of shift work on sleeping quality, hypertension and diabetes in retired workers. PLoS One 2013;8(8): e71107
  11. Han SJ, Joo EY. Circadian rhythm sleep disorders. J Kor Sleep Soc 2008;5(2):74-81
  12. Jeon HJ, Kim JH, Kim BN, Park SJ, Fava M et al. Sleep quality, posttraumatic stress, depression, and human errors in train drivers: a population-based nationwide study in South Korea. Sleep 2014;37(12):1969-1975
  13. Kim YG, Yoon DY, Kim JI, Chae CH, Hong YS et al. Effects of health on shift-work: general and psychological health, sleep, stress, quality of life. Korean J Occup Environ Med 2002;14(3):247-256
  14. Son M, Kong JO, Koh SB, Kim J, Harma M. Effects of long working hours and the night shift on severe sleepiness among workers with 12-hour shift systems for 5 to 7 consecutive days in the automobile factories of Korea. J Sleep Res 2008 ;17(4):385-394
  15. Sohn SI, Kim DH, Lee MY, Cho YW. The reliability and validity of the Korean version of the Pittsburgh Sleep Quality Index. Sleep Breath 2012;16(3):803-812
  16. Uehli K, Mehta AJ, Miedinger D, Hug K, Schindler C et al. Sleep problems and work injuries: a systematic review and meta-analysis. Sleep Med Rev.2014 ;18(1):61-73
  17. Waage S, Pallesen S, Moen BE, Bjorvatn B. Shift work and age in petroleum offshore industry. Int Marit Health 2010;62(4):251-257
  18. Wagstaff AS, Sigstad Lie JA. Shift and night work and long working hours - a systematic review of safety implications. Scand J Work Environ Health 2011; 37(3):173-185