Working hours and all-cause mortality in relation to the EU Working Time Directive: a Danish cohort study

Background: In keeping with the need to protect the safety and health of workers, the EU Working Time Directive stipulates that a worker's average working time for each 7-day period, including overtime, does not exceed 48 h. It has, however, not been settled whether or not the threshold at 48 working hours a week is low enough to protect against excess mortality from long work weeks. The aim of the present study was to examine all-cause mortality in relation to weekly working hours among employees in the general population of Denmark. A special attention was given to mortality rates among employees with moderately long work weeks, 41-48 h. Methods: Interview data from cohorts of 20-64 year-old employees were drawn from the Danish Labour Force Survey. The participants (N= 159 933) were followed through national registers from the end of the calendar year of the interview (1999-2013) until the end of 2014. Rate ratios (RRs) for all-cause mortality were estimated as a function of weekly working hours while controlling for age, sex, social class, night-time work and calendar year. Results: We found 3374 deaths during an average follow-up time of 7.7 years. With 32-40 working hours a week as reference, the RRs for all-cause mortality were 0.75 (95% CI: 0.66-0.85) for 41-48 and 0.92 (0.80-1.05) for > 48 h. Conclusion: Mortality rates in Denmark are significantly lower among employees with moderately long work weeks than they are among full-time employees without overtime work.