EEG-Based Sleep Staging Analysis with Functional Connectivity.

Hui Huang,Jiajia Tang,Jianhai Zhang,Lei Zhu,Li Zhu,Wanzeng Kong,Xu Lei,Guang Lin

doi:10.3390/s21061988

Abstract

Sleep staging is important in sleep research since it is the basis for sleep evaluation and disease diagnosis. Related works have acquired many desirable outcomes. However, most of current studies focus on time-domain or frequency-domain measures as classification features using single or very few channels, which only obtain the local features but ignore the global information exchanging between different brain regions. Meanwhile, brain functional connectivity is considered to be closely related to brain activity and can be used to study the interaction relationship between brain areas. To explore the electroencephalography (EEG)-based brain mechanisms of sleep stages through functional connectivity, especially from different frequency bands, we applied phase-locked value (PLV) to build the functional connectivity network and analyze the brain interaction during sleep stages for different frequency bands. Then, we performed the feature-level, decision-level and hybrid fusion methods to discuss the performance of different frequency bands for sleep stages. The results show that (1) PLV increases in the lower frequency band (delta and alpha bands) and vice versa during different stages of non-rapid eye movement (NREM); (2) alpha band shows a better discriminative ability for sleeping stages; (3) the classification accuracy of feature-level fusion (six frequency bands) reaches 96.91% and 96.14% for intra-subject and inter-subjects respectively, which outperforms decision-level and hybrid fusion methods.

Highlights

With social pressure increasing in this high-speed development era, more and more people are faced with deep sleeping problems
In 1968, R&K [3] identified sleep staging into awake, rapid eye movement (REM) and non-rapid eye movement (NREM) stages, and NREM is further subdivided into four stages: S1, S2, S3, and S4
The phase-locked value (PLV) values are significantly decreased as the frequency bands increase, from delta to gamma bands for REM, N2 and N3 sleep stages

Summary

Introduction

With social pressure increasing in this high-speed development era, more and more people are faced with deep sleeping problems. Clinical sleep staging is still based on visual inspection by sleep experts for decades according to the duration and proportion of special brain waves. Such waves during sleep include delta waves, alpha waves, sleep spindle waves and K-complex waves. Delta waves are slow waves, mainly appearing in N2 and N3 stages with different proportions. The frequency range of the alpha wave (8–13 Hz) and sleep spindle wave (12.5–15.5 Hz) is partially overlapping. Alpha waves generally appears in the REM stage

Methods

Results

Discussion

Conclusion