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Occup Environ Med. 2005 September; 62(9): 588–597.
PMCID: PMC1741083

The impact of overtime and long work hours on occupational injuries and illnesses: new evidence from the United States


Aims: To analyse the impact of overtime and extended working hours on the risk of occupational injuries and illnesses among a nationally representative sample of working adults from the United States.

Methods: Responses from 10 793 Americans participating in the National Longitudinal Survey of Youth (NLSY) were used to evaluate workers' job histories, work schedules, and occurrence of occupational injury and illness between 1987 and 2000. A total of 110 236 job records were analysed, encompassing 89 729 person-years of accumulated working time. Aggregated incidence rates in each of five exposure categories were calculated for each NLSY survey period. Multivariate analytical techniques were used to estimate the relative risk of long working hours per day, extended hours per week, long commute times, and overtime schedules on reporting a work related injury or illness, after adjusting for age, gender, occupation, industry, and region.

Results: After adjusting for those factors, working in jobs with overtime schedules was associated with a 61% higher injury hazard rate compared to jobs without overtime. Working at least 12 hours per day was associated with a 37% increased hazard rate and working at least 60 hours per week was associated with a 23% increased hazard rate. A strong dose-response effect was observed, with the injury rate (per 100 accumulated worker-years in a particular schedule) increasing in correspondence to the number of hours per day (or per week) in the workers' customary schedule.

Conclusions: Results suggest that job schedules with long working hours are not more risky merely because they are concentrated in inherently hazardous industries or occupations, or because people working long hours spend more total time "at risk" for a work injury. Strategies to prevent work injuries should consider changes in scheduling practices, job redesign, and health protection programmes for people working in jobs involving overtime and extended hours.

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Selected References

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  • Hayashi T, Kobayashi Y, Yamaoka K, Yano E. Effect of overtime work on 24-hour ambulatory blood pressure. J Occup Environ Med. 1996 Oct;38(10):1007–1011. [PubMed]
  • Iwasaki K, Sasaki T, Oka T, Hisanaga N. Effect of working hours on biological functions related to cardiovascular system among salesmen in a machinery manufacturing company. Ind Health. 1998 Oct;36(4):361–367. [PubMed]
  • BUELL P, BRESLOW L. Mortality from coronary heart disease in California men who work long hours. J Chronic Dis. 1960 Jun;11:615–626. [PubMed]
  • Emdad R, Belkic K, Theorell T, Cizinsky S. What prevents professional drivers from following physicians' cardiologic advice? Psychother Psychosom. 1998 Jul-Oct;67(4-5):226–240. [PubMed]
  • Kageyama T, Nishikido N, Kobayashi T, Kurokawa Y, Kaneko T, Kabuto M. Long commuting time, extensive overtime, and sympathodominant state assessed in terms of short-term heart rate variability among male white-collar workers in the Tokyo megalopolis. Ind Health. 1998 Jul;36(3):209–217. [PubMed]
  • Liu Y, Tanaka H. Overtime work, insufficient sleep, and risk of non-fatal acute myocardial infarction in Japanese men. Occup Environ Med. 2002 Jul;59(7):447–451. [PMC free article] [PubMed]
  • RUSSEK HI, ZOHMAN BL. Relative significance of heredity, diet and occupational stress in coronary heart disease of young adults; based on an analysis of 100 patients between the ages of 25 and 40 years and a similar group of 100 normal control subjects. Am J Med Sci. 1958 Mar;235(3):266–277. [PubMed]
  • Sokejima S, Kagamimori S. Working hours as a risk factor for acute myocardial infarction in Japan: case-control study. BMJ. 1998 Sep 19;317(7161):775–780. [PMC free article] [PubMed]
  • Uehata T. Long working hours and occupational stress-related cardiovascular attacks among middle-aged workers in Japan. J Hum Ergol (Tokyo) 1991 Dec;20(2):147–153. [PubMed]
  • Akerstedt T, Fredlund P, Gillberg M, Jansson B. A prospective study of fatal occupational accidents -- relationship to sleeping difficulties and occupational factors. J Sleep Res. 2002 Mar;11(1):69–71. [PubMed]
  • Park J, Kim Y, Chung HK, Hisanaga N. Long working hours and subjective fatigue symptoms. Ind Health. 2001 Jul;39(3):250–254. [PubMed]
  • Proctor SP, White RF, Robins TG, Echeverria D, Rocskay AZ. Effect of overtime work on cognitive function in automotive workers. Scand J Work Environ Health. 1996 Apr;22(2):124–132. [PubMed]
  • Rosa RR. Extended workshifts and excessive fatigue. J Sleep Res. 1995 Dec;4(S2):51–56. [PubMed]
  • Maruyama S, Kohno K, Morimoto K. [A study of preventive medicine in relation to mental health among middle-management employees (Part 2)--effects of long working hours on lifestyles, perceived stress and working-life satisfaction among white-collar middle-management employees]. Nihon Eiseigaku Zasshi. 1995 Oct;50(4):849–860. [PubMed]
  • Glass J, Fujimoto T. Housework, paid work, and depression among husbands and wives. J Health Soc Behav. 1994 Jun;35(2):179–191. [PubMed]
  • Shields M. Long working hours and health. Health Rep. 1999 Autumn;11(2):33–55(Fre). [PubMed]
  • Bergqvist U, Wolgast E, Nilsson B, Voss M. Musculoskeletal disorders among visual display terminal workers: individual, ergonomic, and work organizational factors. Ergonomics. 1995 Apr;38(4):763–776. [PubMed]
  • Fredriksson K, Alfredsson L, Köster M, Thorbjörnsson CB, Toomingas A, Torgén M, Kilbom A. Risk factors for neck and upper limb disorders: results from 24 years of follow up. Occup Environ Med. 1999 Jan;56(1):59–66. [PMC free article] [PubMed]
  • Lipscomb Jane A, Trinkoff Alison M, Geiger-Brown Jeanne, Brady Barbara. Work-schedule characteristics and reported musculoskeletal disorders of registered nurses. Scand J Work Environ Health. 2002 Dec;28(6):394–401. [PubMed]
  • Rosenstock SJ, Andersen LP, Rosenstock CV, Bonnevie O, Jørgensen T. Socioeconomic factors in Helicobacter pylori infection among Danish adults. Am J Public Health. 1996 Nov;86(11):1539–1544. [PubMed]
  • Kawakami N, Araki S, Takatsuka N, Shimizu H, Ishibashi H. Overtime, psychosocial working conditions, and occurrence of non-insulin dependent diabetes mellitus in Japanese men. J Epidemiol Community Health. 1999 Jun;53(6):359–363. [PMC free article] [PubMed]
  • Ettner SL, Grzywacz JG. Workers' perceptions of how jobs affect health: a social ecological perspective. J Occup Health Psychol. 2001 Apr;6(2):101–113. [PubMed]
  • Nylén L, Voss M, Floderus B. Mortality among women and men relative to unemployment, part time work, overtime work, and extra work: a study based on data from the Swedish twin registry. Occup Environ Med. 2001 Jan;58(1):52–57. [PMC free article] [PubMed]
  • Spurgeon A, Harrington JM, Cooper CL. Health and safety problems associated with long working hours: a review of the current position. Occup Environ Med. 1997 Jun;54(6):367–375. [PMC free article] [PubMed]
  • van der Hulst Monique. Long workhours and health. Scand J Work Environ Health. 2003 Jun;29(3):171–188. [PubMed]
  • Lowery JT, Borgerding JA, Zhen B, Glazner JE, Bondy J, Kreiss K. Risk factors for injury among construction workers at Denver International Airport. Am J Ind Med. 1998 Aug;34(2):113–120. [PubMed]
  • Macias DJ, Hafner J, 2nd, Brillman JC, Tandberg D. Effect of time of day and duration into shift on hazardous exposures to biological fluids. Acad Emerg Med. 1996 Jun;3(6):605–610. [PubMed]
  • Gander PH, Merry A, Millar MM, Weller J. Hours of work and fatigue-related error: a survey of New Zealand anaesthetists. Anaesth Intensive Care. 2000 Apr;28(2):178–183. [PubMed]
  • Simpson CL, Severson RK. Risk of injury in African American hospital workers. J Occup Environ Med. 2000 Oct;42(10):1035–1040. [PubMed]
  • McCartt AT, Rohrbaugh JW, Hammer MC, Fuller SZ. Factors associated with falling asleep at the wheel among long-distance truck drivers. Accid Anal Prev. 2000 Jul;32(4):493–504. [PubMed]
  • Baker K, Olson J, Morisseau D. Work practices, fatigue, and nuclear power plant safety performance. Hum Factors. 1994 Jun;36(2):244–257. [PubMed]
  • Ong CN, Kogi K. Shiftwork in developing countries: current issues and trends. Occup Med. 1990 Apr-Jun;5(2):417–428. [PubMed]
  • Hänecke K, Tiedemann S, Nachreiner F, Grzech-Sukalo H. Accident risk as a function of hour at work and time of day as determined from accident data and exposure models for the German working population. Scand J Work Environ Health. 1998;24 (Suppl 3):43–48. [PubMed]
  • Folkard Simon, Akerstedt Torbjörn. Trends in the risk of accidents and injuries and their implications for models of fatigue and performance. Aviat Space Environ Med. 2004 Mar;75(3 Suppl):A161–A167. [PubMed]
  • Tucker P, Folkard S, Macdonald I. Rest breaks and accident risk. Lancet. 2003 Feb 22;361(9358):680–680. [PubMed]
  • Akerstedt T, Fredlund P, Gillberg M, Jansson B. A prospective study of fatal occupational accidents -- relationship to sleeping difficulties and occupational factors. J Sleep Res. 2002 Mar;11(1):69–71. [PubMed]
  • Nolting HD, Berger J, Schiffhorst G, Genz HO, Kordt M. Psychischer Stress als Risikofaktor für Arbeitsunfälle bei Pflegekräften im Krankenhaus. Gesundheitswesen. 2002 Jan;64(1):25–32. [PubMed]
  • Voss M, Floderus B, Diderichsen F. Physical, psychosocial, and organisational factors relative to sickness absence: a study based on Sweden Post. Occup Environ Med. 2001 Mar;58(3):178–184. [PMC free article] [PubMed]
  • Lees RE, Laundry BR. Comparison of reported workplace morbidity in 8-hour and 12-hour shifts in one plant. J Soc Occup Med. 1989 Autumn;39(3):81–84. [PubMed]
  • Krause N, Lynch J, Kaplan GA, Cohen RD, Goldberg DE, Salonen JT. Predictors of disability retirement. Scand J Work Environ Health. 1997 Dec;23(6):403–413. [PubMed]
  • Iwasaki K, Sasaki T, Oka T, Hisanaga N. Effect of working hours on biological functions related to cardiovascular system among salesmen in a machinery manufacturing company. Ind Health. 1998 Oct;36(4):361–367. [PubMed]

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