Abstract
Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming information required to update the long-term mnemonic storage and to manipulate new elements in order to solve problems and make decisions. Nevertheless, the influence of sleep deprivation on working memory has scarcely been studied. In this study we evaluated working memory using the N-back test after increasing periods of wakefulness. Healthy young males were kept awake for 36 hours and the two N-back tasks with low (1-Back) and high (3-Back) levels of complexity were applied every 6 hours. Additionally, salivary cortisol was determined along the study. Unlike the control non-deprived participants, the sleep deprived volunteers showed a significant decrease in their efficiency to solve the 1-Back task after 24 hours of sleep deprivation. However, no differences were observed after 30 and 36 hours of sleep deprivation. Concerning the 3-Back task no differences were observed after sleep deprivation. Regarding reaction time, the deprived group manifested slower responses for the 1-Back task and for the 3-Back task after 30 hours and 36 hours of sleep deprivation, respectively. Cortisol levels presented the normal daily oscillation and no differences were observed between groups. This data suggests that sleep deprivation affects basal states of attention instead of working memory while performing simple tasks. The impact of sleep deprivation on the cognitive performance depends on the moment of day when the task is applied and the complexity of the tests used to assess these mnemonic skills.
Highlights
Sleep is an essential process for normal human development and daily cognitive performance [1,2]
The current urban life-style includes assorted and nocturnal schedules and activities that elicit stressful conditions as well as alterations in the sleep-wake rhythm [3,4]. Both stress and sleep deprivation have a negative impact on the satisfactory function of several cognitive processes, such as, attention, motor coordination, learning, language understanding and memory [5,6,7,8,9]
Working memory refers to a short-term reserve of incoming information required to update the long-term mnemonic storage and to manipulate new elements to solve problems and make decisions [12,13,14,15,16]
Summary
Sleep is an essential process for normal human development and daily cognitive performance [1,2]. The current urban life-style includes assorted and nocturnal schedules and activities that elicit stressful conditions as well as alterations in the sleep-wake rhythm [3,4]. Both stress and sleep deprivation have a negative impact on the satisfactory function of several cognitive processes, such as, attention, motor coordination, learning, language understanding and memory [5,6,7,8,9]. Working memory constitutes one of the main mnemonic processes it has scarcely been studied in relation to sleep disorders or disturbances. Working memory refers to a short-term reserve of incoming information required to update the long-term mnemonic storage and to manipulate new elements to solve problems and make decisions [12,13,14,15,16]
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