Book excerpt: Fatigue is a recognized problem in many facets of the human enterprise. It is not confined to any one area of activity but enters all situations in which humans have to perform for extended intervals of time. Most problematic are the circumstances in which obligatory action is continuous and the results of failure are evidently serious or even catastrophic. Therefore, the modern media especially highlights fatigue-related failures in industries such as transportation, materials processing and healthcare. It can be, and indeed is, no coincidence that most of the spectacular failures in process control that have resulted in the world's largest industrial accidents have occurred in the small hours of the morning when the circadian rhythm is lowest and operator fatigue itself peaks. While there have been legislative efforts made at state, federal and international levels to regulate working hours of employees, the appropriate implementation of such legislation is still a long way off. The Handbook of Operator Fatigue provides a comprehensive account of the subject to serve as the definitive reference work for researchers, students and practitioners alike. The volume features 30 chapters written by experts from around the world to address each important facet of fatigue, including: the scale of the fatigue problem (Section I), the nature of fatigue (Section II), how to assess fatigue (Section III), the impact of fatigue on health (Section IV), fatigue in the workplace (Section V), the neurological basis of fatigue (VI), sleep disorders (VII), and the design of countermeasures to fatigue (VIII).