Impairments in Sustained Attention and the Efficiency of Psychomotor Activity during Episodes of Spontaneous Awakening from Daytime Sleep

Objectives. To investigate disturbances of sustained attention (vigilance) and to identify their objective characteristics in conditions of sleep inertia after spontaneous awakening from daytime sleep. Materials and methods. A total of 15 essentially healthy subjects (students) took part in investigations of disturbances of sustained attention using a bimanual psychomotor test after awakening from the second stage of daytime sleep. The numbers of button-presses with the right and left hands were used as a measure of disturbances: incorrect responses (a smaller number) vs. responses corresponding to the instructions. Attention was taken to be impaired if the subject did not fully reproduce the test tasks. Complete test performance was regarded as a behavioral marker of the absence of disturbances. Electroencephalography (EEG) power characteristics recorded at different levels of stability of attention in subjects were analyzed. Results. Disturbances of the stability of attention (vigilance) on awakening, i.e., in conditions of sleep inertia, were accompanied by generalized high power levels of slow-wave oscillations and lower values of the low-frequency α rhythm. These findings indicate differences in cerebral activation which disrupt the stability of attention in subjects in these conditions. Stability of attention was found not to affect performance of a task consisting of switching psychomotor activity from one hand to the other. At the same time, control over the number of presses stipulated by the instruction during switching in conditions with full performance of test tasks requires more cerebral resources, which is reflected in an increase in the power of the γ rhythm during this period. Conclusions. The neural correlates of impaired stability of attention (vigilance) produced by awakening discovered here make it possible to create a set of markers which can be used to optimize the sleep–waking cycle in conditions of restricted sleep and working shifts in the sleep period. They can also be used in clinical practice when patients complain of cognitive impairments arising from sleep disorders. © 2025 Elsevier B.V., All rights reserved.