Inter-scorer reliability of sleep assessment using EEG and EOG recording system in comparison to polysomnography

There are increasing needs for self-applicable methods assessing sleep in clinical and non-clinical settings. This study aimed to investigate the inter-scorer reliability for the sleep stage scoring and for the sleep variable assessments in the portable electroencephalography (EEG) and electro-oculography (EOG) recording system. Sleep recordings were performed simultaneously with polysomnography (PSG) and portable EEG/EOG recordings in 14 healthy adults. The inter-scorer concordance of the sleep stage scoring was assessed in the two recording methods. Sleep variables were compared between the two methods using the Bland–Altman plots in each scorer. The overall inter-scorer concordance rate of sleep stage scoring for the EEG/EOG data was 85.5 %, and the Cohen’s κ was 0.80 (p < 0.001), being equivalent to those for the PSG data (89.2 %, 0.85, p < 0.001) while that for StageN1 was relatively low (EEG/EOG 60.1 %, PSG 71.7 %). In both scorers, Bland–Altman plots showed that the mean difference between sleep variables obtained from the two systems was within the acceptable range although the inter-class correlations between the two systems were lower for StageN2 or StageR in either scorer. Although the results suggest that the sufficient inter-scorer reliability can be obtained with the EEG/EOG recording system based on manual sleep stage scoring in healthy young adults, the nature of the EEG/EOG recording system can influence the precisions in manually assessing sleep architectures in comparison to PSG.