*Corresponding author e-mail: jacdel78@hotmail.com Introduction: Sleep deprivation affects different cognitive processes. Working memory is a cognitive process that temporarily maintains information to perform multiple complex tasks such as reading, learning and reasoning. This cognitive process has two components: phonological and visuospatial storages. The phonological storage component is important for the processing of verbal information, whereas the visuoespacial storage is relevant for the processing of visual tasks, such as driving a car, space navigation and solving mathematical problems. The objective of the present study is to determine the effect of 24-h sleep deprivation on the components of working memory. Methods: 20 undergraduate students participated, age 17.80±1.06, (16-20) years; they attended classes in the morning shift. They were divided in two groups. A control (non-sleepdeprived) group and a 24-h sleep-deprived group. Both groups were recorded in the laboratory at 06:00h, 08:00h, 10:00h and 12:00h. The phonological memory task consisted in a set of 4 upper-case letters displayed simultaneously on the monitor's screen, followed by one lower-case letter; the participants had to indicate if the lower-case letter matched one of the 4 upper-case letters previously displayed. The visuospatial memory task was similar, but instead of letters, 3 dots were displayed simultaneously in different places of the screen, followed by a circle; the participants had to indicate if the circle appeared in any of the places where the dots were previously shown. Results: In the phonological storage component of working memory, there was a reduction of correct responses with time of day, in both groups (F= 3.8953, p < 0.05). In the visuospatial storage component of working memory, the sleep deprived group showed an increase in reaction time (F= 9.470, p < 0.01), there was also an increase in reaction time with time of day, in both groups (F= 4.366, p < 0.01). Conclusion: In conclusion, 24-h sleep deprivation impairs the visuospatial storage component of working memory during morning hours; this can decrease efficiency in many activities, such as driving a car, space navigation and solving mathematical problems. Publication History Article published online: 16 June 2026 © 2009. Brazilian Sleep Academy. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil
Angel et al. (Thu,) studied this question.