General mortality in relation to the EU Working Time Directive: a Danish study protocol

The European Parliament and the Council of the European Union recognises night-time work and long working hours as occupational safety and health hazards. The issue is addressed in the EU Working Time Directive, which, among other things, stipulates that member states shall take the measures necessary to ensure that the average working time for each 7-day period, including overtime, does not exceed 48 hours. The directive also contains a series night-time work regulations. The purpose of the directive, which has been in force since 1993, with slight amendments in the year 2000 and 2003, is to protect the safety and health of workers.

If the intent of the directive is fulfilled then the night-time regulations should be sufficient to protect against adverse health effects from night-time work and the 48 hour limit should be sufficient to protect against adverse health effects from long working hours. A recent study among female nurses in Denmark found, however, an increased mortality among night-time workers, which has raised concerns about the sufficiency of the directive.

Neither long working hours nor night-time work has been studied in relation to all-cause mortality in the general working population of Denmark. The present project will therefore examine if all-cause mortality rates depend on weekly working hours and night-time work among employees in the general working population of Denmark.

The present study protocol gives a detailed description of the data material, inclusion criteria, statistical models, hypotheses and test criteria of the study and, in accordance with recognised rules of good scientific and statistical practice; the protocol is published before the exposure data of the study are linked to the outcome data.