Dynamic Sleep Architecture Revealed: Sleep Auditory Evoked Potentials from N100 to P900

Abstract

Background: The research landscape in sleep is currently shifting toward minute changes in brain functioning during different stages. This fine approach necessitates a dynamic assessment as in the case of electrophysiology. The present study aimed to investigate brain responsiveness during different stages and times of nocturnal sleep using auditory evoked potentials (AEPs). Materials and Methods: Sleep recordings of 18 volunteer subjects were analyzed. During sleep recordings, auditory stimuli were presented in the ear channels. Sleep stages were scored according to the American Academy of Sleep Medicine system. AEPs were analyzed in nonrapid eye movement sleep stages. Alterations of N100, P200, N300, P450, N550, and P900 waveforms were investigated in the first and second halves of sleep duration. Results: N100 amplitude was higher in light sleep, both in the first and the second halves of the night (sleep duration). The amplitude of P900 was higher in the deep sleep stage in both halves. Significant amplitude reductions were found in N100, P200, P450, and P900 in the second half of the sleep. Conclusions: The changes found suggest that they are related to the dynamics of sensory processing to maintain functional sleep. The findings of the present study emphasize that in the course of sleep, both the proportions of sleep stages and the microarchitecture within the stages alter between the first and second halves of sleep.