ABSTRACT
The term shift is used in a variety of ways. In the most general usage, shift refers to the hours of a given day that an individual or a group of individuals is scheduled to be in the workplace. Often, this term is used in a more restricted way, where shift refers only to a specific category of work hours, defined by practices at a specified location. In many cases these hours are viewed as undesirable, nontraditional, exceptional, or unusual. The more general usage will be used here, since process and practice developments in recent years make it very difficult to define what is exceptional or unusual. Presser (1995) has clearly demonstrated that work hours for the majority of Americans are not restricted to the traditional image of regular daytime weekday work of 35 to 40 hours per week.
