ABSTRACT
The ergonomic problem with regard to shiftwork is that of enabling the individual to work at abnor-
mal hours, an activity which runs both counter to his or her own biology (Homo sapiens is a diurnal
species) and counter to the surrounding society which is structured to protect the sleep of day
workers, but not that of night workers, and expects evenings and weekends to be free for social, reli-
gious, athletic, and cultural events. Moreover, shiftwork is not simply restricted to a very small group
of people who can be carefully selected or self-selected to experience minimal problems. Neither is it
restricted to the youngest and fittest of workers who can bid their way out of abnormal hours when
they advance into their middle age. Employment trends, particularly in the manufacturing sector, now
dictate that the “bidding out of shiftwork by seniority” option often no longer applies. For many
middle-aged and late middle-aged workers the only option is between shiftwork and no work.
Thus, approximately one fifth of all employees are engaged in some form of work that requires
their presence outside of the “standard” 7 am to 6 pm working day on a regular basis, and can
thus be regarded as “shiftworkers.”
