Impairments in sustained attention and the efficiency of psychomotor activity during episodes of spontaneous awakening from daytime sleep

OBJECTIVE: To study attention span (vigilance) disorders and identify their objective characteristics in a sleep inertia state after spontaneous awakening from daytime sleep. MATERIAL AND METHODS: In 15 healthy subjects (students), a bimanual psychomotor test was used to analyze attention span disorders after waking up from the stage 2 of daytime sleep. The number of button presses with the right and left hands was used to assess the disorders: compliant and non-compliant (a smaller number) with the instruction. Attention was considered impaired if a subject did not fully follow the test instructions. Complete test was considered as a behavioral marker of no impairment. The power characteristics of electroencephalography (EEG), which was recorded with different attention span in a subject, were analyzed. RESULTS: Attention span (vigilance) disorders upon awakening in the sleep inertia state are accompanied by generalized higher power of slow wave activity and lower power of the low-frequency alpha rhythm. These findings indicate differences in brain activation that impair the subjects' attention span in this state. The attention span does not affect the psychomotor activity switching from one hand to the other. Of note, the control over the instruction-based number of presses during switching in subjects who completed the test requires more brain resources, which is reflected in an increase in the gamma rhythm power during the test. CONCLUSION: The detected neurocorrelates of impaired attention span (vigilance) due to the awakening state helps to create a set of markers that can be used to optimize the sleep-wake cycle in case of restrictions and shifts in the sleep period. They can also be used in clinical practice when patients complain of cognitive impairment due to sleep disorders.