Definition: Shift work
The question on shift work is addressed only to employees. Work shifts are defined as two or more distinct periods of work within 24-hour day between which employees are regularly rotated. An employee is therefore classified as shift worker if he/she works two or more different work shifts. Persons working fixed hours (i.e. whose working hours do not vary significantly) are not considered as shift workers.
Eurostat, "Labour force survey: Methods and definitions, 1998 Edition", Office for Official Publications of the European Communities, Luxembourg, 1999, p.66