Nomenclature discussion

Working time nomenclature is poorly defined in the literature, and significant international differences in definitions exist.

The Working Time Society aims to develop operational definitions (when possible) for working time nomenclature, monitor its use, and recommend changes  when needed.

In addition, they will encourage Editors and symposium authors to use the WTS nomenclature.

Weekend Work

Weekend work impacts the social weekly rhythm. Examples are:

  • Friday evening work that ends after 17:00, also the night shift into
  • Saturday work
  • Sunday work
  • Monday morning work that starts so early that it impacts the social behaviour of Sunday evening


A shift designates the beginning and end of a period of presence at the work place.

  • It can be longer than a day
  • It can include one or several breakswhich may be unpaid.

Shifts with one or morebreaks in between where at least one break is longer than an hour are called split shifts.

If time of none-work is more than 8 hours it is not a shift anymore but two shifts.



Nightwork is work at times that have substantial impact on the sleep wake cycle. The baseline is daytime work. 
* This can be classical work in the night but also very early morning work (e.g. start of work at
* If work ends after 2am this is to be considered nightwork.


It´s an interesting approach; you change from the stress point of the analysis to the strain one. This way the consideration happens at the individual level. However, it might be difficult e.g. to define who gets the shift bonus (who experience the substantial impact on the sleep wake cycle?).

Materials and Arguments considered:

Definition used within the European Union

DEFINITION: Directive 2003/88/EC of the European Parliament and of the Council – Article 2 

3. “night time” means any period of not less than seven hours, as defined by national law, and which must include, in any case, the period between midnight and 5.00;

4. “night worker” means:

(a) on the one hand, any worker, who, during night time, works at least three hours of his daily working time as a normal course; and

(b) on the other hand, any worker who is likely during night time to work a certain proportion of his annual working time, as defined at the choice of the Member State concerned:

(i) by national legislation, following consultation with the two sides of industry; or

(ii) by collective agreements or agreements concluded between the two sides of industry at national or regional level;



One of the drawbacks of this definition is, that national law that defines such limit (e.g. a minimal number of night shifts to be a night worker and to get the corresponding benefits) makes it difficult to reduce night work under that threshold. Employees may resist a reduction of nightwork under this threshold.



“Shiftwork” Definition

To be decided at the XIXth International Symposium on Shiftwork and Working Time will be in Venice 2009

Shiftwork is work at times that have substantial impact on the sleep wake cycle or are in conflict with basic social rhythms.

NOTE: It is not important whether it is permanent rhythm or whether persons share a workplace over time.
The position of working time is the key-element.

Materials and Arguments considered

Definition used within the European Union

DEFINITION: Directive 2003/88/EC of the European Parliament and of the Council – Article 2:

“5. “shift work” means any method of organising work in shifts whereby workers succeed each other at the same work stations according to a certain pattern, including a rotating pattern, and which may be continuous or discontinuous, entailing the need for workers to work at different times over a given period of days or weeks;”

DISCUSSION: This definition has severe shortcomings

  1. Some permanent shift systems that are used only at special hours (e.g. cleaning) are excluded
  2. Shift systems where shifts overlap strongly (e.g. one shiuft starting at 8:00, two further shifts starting at 10:00, etc. may not always result in systems where workers succeed each other.
  3. The concept of work station may be problematic for some occupations (e.g., running a computer center people habe their inidivual work station but may succeed (in parts of) tasks.


Evening Work

Evening Work

Evening work impacts on the social daily rhythm. Examples are:

  • Work ending after 17:00
  • Nightwork can be considered to influence social activity in the evening




as defined by the Working Time Society

A break designates the beginning and end of a period of non-work, as part of the shift that is designated to recovery.

  • If breaks become very long they became rest times.