Sleep is essential for physical and mental recovery, also for some processes like memory, attention and language. Sleep deprivation (SD) affects selective attention and concentration. The SD is inherent in the medical training, however, it is unclear the role of night shifts in medical students, as they do not meet a pure academic objective, and instead has shown the association of SD with declining health, productivity and some accidents, or some alterations in different activities. METHODS: An observational longitudinal cohort analytic study, measurement three stages to 180 medical students at the University of Rosario, which sought to assess selective attention and concentration by applying the d2 test, internationally validated for that purpose. RESULTS: A total of 180 students, 115 women and 65 men, aged between 18 and 26 years (mean 21), At baseline slept on average 7. 9 hours, and this was reduced to 5. 8 and 6. 3 in the second and third stages respectively. The average hours of nightly sleep, decreased in the second and third time (p < 0. 001) was also found by applying d2 test, there was a weak direct significant correlation between the average hours nocturnal sleep, and average performance as the test concentration (r = 0. 168, p = 0. 029). CONCLUSIONS: The night shifts performance, and the SD resulting, with sleep periods less than 7. 2 hours, has an important impact on selective attention
