Background: Fatigue and mental performance are closely related parameters of higher integrative brain functions. These indices of higher brain functioning had been implicated in general intellectual abilities, effectiveness of the diurnal performance, especially in people with active brain development and high cognitive demand such as young adults and students. Unfortunately, there is a paucity of data on the effects of alcohol consumption on the fatigue and mental performance level of young adults (students) with different attitudes to alcohol consumption. The aim of this study was to investigate the differences in fatigue and mental performance of young adults (university medical students) with different attitudes to alcohol consumption. Materials and Methods: Altogether, 27 participants (alcohol users and non-alcohol users, males, age range 20-29 years) volunteered for the study. The first period of this study took 6.5 h of mental activities on fasting. Thereafter, for a period of rest (2 h) following administration of glucose (75 g), functions of the participants were examined. Alcohol users did not use alcoholic drinks of any composition for 1-4 weeks before the study. All participants were administered standardized questionnaires (alcohol use disorders identification test, WAM, WAM-8, etc.), and assigned specific tasks in four phases. Standard psychophysiological tasks were administered to them, so as to produce a working environment that would necessary produce fatigue on the long-run. The rate of error commission was also examined. Blood glucose sampling was done at 2 h intervals. The statistical level for significance was set at P ≤ 0.05. Results: Comparative analysis of the objective (number of errors in the test of attention and all five tests) and subjective (scores on “WAM” and “WAM-8”) parameters of fatigue and mental performance in young people (students) at baseline and in the course of mental work, and the rest after work, indicates a fast development and high level of fatigue in alcohol users. In 52.6% respondents who reported alcohol use, 2 h of rest and consumption of 75 g of glucose were inadequate for full recovery of their functional state and performance following fatigue, caused by prolonged work on fasting. In 38.9% cases, alcohol users had signs of chronic fatigue. Conclusion: The high level of fatigue and impaired performance in alcohol users indicate unsafe use of even low-to-moderate quantity of alcohol by young students.