EEG Spectral Analysis in Gray Zone Between Healthy and Insomnia

TL;DR

This study explores EEG patterns in individuals with subjective sleep difficulties who do not meet clinical insomnia criteria, revealing neural activity markers that may indicate risk for developing chronic insomnia despite normal sleep architecture.

Contribution

It identifies specific EEG spectral features in gray zone individuals that could serve as early indicators of insomnia risk, bridging subjective complaints and objective neural markers.

Findings

Increased delta and alpha activity during wakefulness in gray zone individuals

Elevated beta and gamma activity in NREM stages 1 and 2

No significant differences in sleep architecture between groups

Abstract

This study investigates the sleep characteristics and brain activity of individuals in the gray zone of insomnia, a population that experiences sleep disturbances yet does not fully meet the clinical criteria for chronic insomnia. Thirteen healthy participants and thirteen individuals from the gray zone were assessed using polysomnography and electroencephalogram to analyze both sleep architecture and neural activity. Although no significant differences in objective sleep quality or structure were found between the groups, gray zone individuals reported higher insomnia severity index scores, indicating subjective sleep difficulties. Electroencephalogram analysis revealed increased delta and alpha activity during the wake stage, suggesting lingering sleep inertia, while non-rapid eye movement stages 1 and 2 exhibited elevated beta and gamma activity, often associated with chronic insomnia. However, these high-frequency patterns were not observed in non-rapid eye movement stage 3 or rapid eye movement sleep, suggesting less severe disruptions compared to chronic insomnia. This study emphasizes that despite normal polysomnography findings, EEG patterns in gray zone individuals suggest a potential risk for chronic insomnia, highlighting the need for early identification and tailored intervention strategies to prevent progression.