The influence of long-term cognitive load on the individual condition (HEM Questionnaire) and also electrophysiological parameters (individual alpha rhythm (IAR), the spectral characteristics of the electroencephalogram (EEG), fatigue index (IS)). Cognitive or mental load was simulated by a series of continuous solutions of various cognitive tasks assigned that were aimed mainly on working memory and attention within the time limit of 2.5 hours. Before and after the test we were making records of background EEG and the participants were completing HEM questionnaires.

Analysis of the results of research conducted by the statistical comparison of the data obtained before and after exercise. The results show that long-term cognitive load significantly tells on the subjective sphere and the activity of the participant. On the electrophysiological level, the load results in a decrease of individual alpha rhythm frequency, a vast increase in the fatigue index, and also the increase of average power of theta, alpha and beta rhythms. Thus, the cognitive load is reflected in the significant shift of brain activity dynamics manifested as quite dynamic parameters of the alpha and beta rhythms power, this being in a more stable performance, such as individual alpha rhythm and the fatigue index. Summing up, a significant mental work leads to a significant increase in the power of slow-wave activity in the brain and the deterioration of the subjective well-being. On the one hand, the results of the research correspond with the literature data and, on the other hand, the results are integrating the data of various studies and consequently provide a more comprehensive view of the process of mental fatigue in terms of the dynamics of the brain.