The aim of this work was to show and describe the effects of fatigue and sleep deprivation in a military environment. The concepts of fatigue and sleep are theoretically described and an understanding of the role of sleep and rest on different physical and psychological processes is made possible. In addition, it was written that meeting the need for sleep and rest contributes to the optimal physical, psychological, emotional and cognitive functioning of military personnel. Furthermore, in this paper, the focus is on understanding the importance of the specifics of military service that are related to the experience of sleep and fatigue. That is why the paper presents results of several studies carried out with the aim of improving programs for the preparation and training of professional military personnel for specific shorter and longer military operations in which extended periods of vigilance are an integral part of military tasks. In addition, from the perspective of the military profession, the use of different sensors and the possible operationalization of fatigue parameter measurements in the army are described.