Long working hours are inversely related to sick leave in the following 3 months: a 4-year registry study
The aim of this study was to investigate the effects of long working hours (≥ 12 h shifts) on sick leave using objective records of shift work exposure and of sick leave.
A total of 1538 nurses (mean age 42.5, SD 12.0; response rate 42%) participated. Payroll and archival sick leave data over a 4-year period were retrieved from employers’ records and aggregated over every third calendar month. A multilevel negative binomial model was used to investigate the effects of exposure to long working hours, on subsequent sick leave rates the following 3 months. Covariates included prior sick leave, number of shifts worked, night and evening shifts, personality, and demographic characteristics.
Exposure to long working hours was associated with fewer sick leave days in the subsequent 3 months [adjusted model, incidence rate ratio (IRR) = 0.946, 95% CI 0.919–0.973, p < 0.001]. The interaction long working hours by a number of work days showed that sick leave days the subsequent 3 months was higher by long shifts when number of shifts was high compared to when number of shifts was low [adjusted model, IRR 1.002, 95% CI 1.000–1.004, p < 0.05].
Long working hours was associated with fewer sick leave days. The restorative effects of extra days off with long working hours are discussed as possible explanations to this relationship.
KeywordsLong working hours Extended daily working hours Long shifts Sick leave Sickness absence
We thank employees at the personnel department at Haukeland University Hospital for their assistance with retrieving the payroll and sick leave data.
ØV, AH, SP, BB, SW, ES and BS took part in planning the study. ØV, AH, ES and SW took part in gathering the data. ØV, AH, SP, BB, SW, ES, BS and EE took part in writing up the manuscript and reporting the work.
The study was partly funded from Nordforsk, Nordic Program on Health and Welfare (74809).
Compliance with ethical standards
The study was approved by the Regional Committee for Medical and Health Research Ethics, Northern Norway (number 2013/526/REK nor) and by the Norwegian Data Inspectorate (13/00569-2/CGN).
Informed consent was obtained from all participants included in the study.
Conflict of interest
The authors declare that they have no conflict of interest.
- Aguirre A, Heitmann A, Imre A, Sirois W, Moore-Ede M (2000) Conversion from 8-h to a 12-h shift schedule. In: Hornberger S, Knauth P, Costa G, Folkard S (eds) Shiftwork in the 21st century. Peter Lang, Frankfurt am Main, pp 113–118Google Scholar
- Estryn-Béhar M, Van der Heijden BI (2012) Effects of extended work shifts on employee fatigue, health, satisfaction, work/family balance, and patient safety. Work (Read Mass) 41:4283–4290Google Scholar
- Jozef D (1990) Morbidity and absenteeism rates of operators connected with duration of shift. In: Costa G, Cesana G, Kogi G, Wedderburn A (eds) Shiftwork: health, sleep and performance. Peter Lang, Frankfurt am MainGoogle Scholar
- Karhula K, Koskinen A, Ojajärvi A, Ropponen A, Puttonen S, Kivimäki M, Härmä M (2018) Are changes in objective working hour characteristics associated with changes in work-life conflict among hospital employees working shifts? A 7-year follow-up. Occup Environ Med. https://doi.org/10.1136/oemed-2017-104785 Google Scholar
- Kerlinger FN (1986) Foundations of behavioral research. CBS Publishing, New YorkGoogle Scholar
- Parent-Thirion A, Fernández Macías E, Hurley J, Vermeylen G (2007) Fourth European working conditions survey. Office for Official Publications of the European Communities, LuxembourgGoogle Scholar
- Presser HB (2006) Employment of a 24/7 economy: challenges for the family. In: Perrons D, Fagan C, McDowell L, Ray K, Ward K (eds) Gender divisions and working time in the new economy: changing patterns of work, care and public policy in Europe and North America. Edward Elgard Publishing, Inc., NorthamptonGoogle Scholar
- Rabe-Hesketh S, Skrondal A (2012) Multilevel and longitudinal modeling using Stata: volume I: continuous responses & volume II: categorical responses, counts, and survival. StataCorp LP, College StationGoogle Scholar
- Thierry H, Jansen B (1998) Work time and behaviour at work. In: Drenth PJD, Thierry H, Wolff CJ (eds) Handbook of work and organizational psychology: work psychology, vol 2. Psychology Press, Hove, pp 89–119Google Scholar