This is a scholarly monograph about the 12 hour shift and how it has benfitted the many shift workers in the oil and chemical industries. It has provided tham with more usable free time and allowed their circadian rythms to suffer less disruption. This was written as part of an internship done at The Wharton School by James T. Wilson in 1976 and 1978 while studying for a Master of Business Administration with a focus on Labor and Human Resources.