Decreased Control and Enhanced Reactivity: Dual Dysregulation Pattern of Cross-Frequency Coupling in Emotional Susceptibility of Non-Clinical Insomnia.

OBJECTIVE

Insomnia involves impaired emotional attention, yet the underlying neurophysiological mechanisms remain unclear. This study investigated neurobehavioral characteristics of emotional processing in insomnia, specifically examining modulations by emotional valence and intensity.

METHODS

Twenty-five individuals with non-clinical insomnia disorder (NCID) and 22 normal controls (NC) performed a two-choice oddball task with emotional images (varying in valence and intensity) during task-state EEG recording. Phase-amplitude coupling (PAC) and time-frequency analyses were utilized to assess neural dynamics.

RESULTS

The NCID group responded averagely slower and showed distinct negative bias, with response being faster to negative versus positive affective images. PAC analysis confirmed a dual dysregulation: the NCID group showed significantly reduced delta-beta coupling in frontal regions and significantly increased theta-beta coupling in occipital regions. Importantly, these coupling alterations were intensity-dependent; the NCID group showed a blunted dynamic range across intensities and lower frontal coupling specifically for high-intensity negative stimuli. Time-frequency analysis further revealed increased posterior theta power in the NCID group, while beta oscillations showed enhanced responses to negative stimuli in both groups.

CONCLUSION

Insomnia is characterized by altered emotional susceptibility involving intensity-dependent alterations in cross-frequency coupling (CFC). These findings clarify the neurophysiological mechanisms of emotional dysfunction in insomnia and highlight CFC as a potential biomarker for emotional regulation impairments.