Article ID: 2102si
The exact functions of the K-complex are underinvestigation; however, the K-complex, unique to Stage 2 sleep, reportedlyplays a role in arousal induction and sleep protection. Event-relatedpotentials (ERPs), appearing when externally evoked K-complexes are observed, have a monomodal (N300-P900 or N550-P900) or a bimodal (N300-P400-N550-P900) morphology. Studies have indicated the involvement of P400 in thesemorphological differences. P400 reflects information processing about externalstimuli, which decays or disappears as sleep-depth increases. We compared theERP waveforms and the functions of auditory evoked K-complex by dividing Stage2 sleep of the first sleep cycle into first and second half sections. Resultsindicated that P400 amplitude attenuated in the second compared to the firsthalf. Concomitantly, we observed a bimodal (N300-P400-N550-P900) ERP waveformin the first half, whereas a monomodal (N300-P900) waveform was observed in thesecond half of the first sleep cycle. These findings suggest that the functionof the K-complex in the first half of Stage 2 sleep might predominantly bearousal-induction, whereas its function in the second half is sleep-protection.
