This updated edition includes fatigue and sleep definitions as well as strategies for the measurement and assessment of fatigue. The aviation performance, mood, and safety problems associated with sleep restriction and circadian disruptions in operational settings are highlighted. The biological bases of fatigue are discussed so that the reader can understand that it is a real physiological phenomenon and not 'just a state of mind'. Both traditional and newly-developed scientifically-valid countermeasures are presented, and a variety of data from diverse sources are included to provide...