A Neurophysiological Picture of the Genesis of Fatigue, Chronic Fatigue, and Overfatigue in Human Operators

The present widespread conceptual model of the neurophysiological picture of human fatigue, chronic fatigue, and overfatigue is limited to the picture of hypoexcitability and development of inhibitory processes in the CNS. The results of this study show that, when fatigue deepens and is followed by chronic fatigue and overfatigue, the inhibitory processes that developed earlier weaken. The speed of nervous processes and their lability increase in this period, exceeding the initial "normal" baseline values; the differential inhibition strengthens. Both main nervous processes weaken; the excitatory process begins to relatively predominate. The equalization and paradoxical phases manifest themselves in the CNS functioning. As fatigue deepens and overfatigue develops, excitability of nervous structures continues decreasing. Interhemispheric asymmetry increases.