Increased high-frequency NREM EEG power associated with mindfulness-based interventions for chronic insomnia: Preliminary findings from spectral analysis.

Objective: Mindfulness-based interventions (MBI) have been shown to reduce subjective symptoms of insomnia but the effects on objective measures remain unclear. The purpose of this study was to examine sleep EEG microarchitecture patterns from a randomized controlled trial of Mindfulness-Based Stress Reduction (MBSR) and Mindfulness-Based Therapy for Insomnia (MBTI).

Methods: Sleep EEG spectral analysis was conducted on 36 participants with chronic insomnia (>6 months) randomized to 8-week MBSR, MBTI, or self-monitoring control (SM). Overnight polysomnography with 6-channel EEG was conducted at baseline, post-treatment, and 6-month follow-up. Spectral power averaged from channels C3/C4 across NREM epochs (excluding N1) was examined for within-group changes and relationships with self-report measures.

Results: Increases in absolute NREM beta (16-25 Hz) power were observed from baseline to post-treatment (p = .02, d = 0.53) and maintained at 6-month follow-up (p = .01, d = 0.57) in the combined MBI groups, and additionally in the gamma (25-40 Hz) range at follow-up for the MBTI group only. No significant changes in these frequency bands were observed for SM. Following mindfulness intervention, NREM beta was positively associated with Five-Facet Mindfulness (FFM) score (rho = 0.37, p = .091) and negatively associated with Insomnia Severity Index (rho = -0.43, p = .047).

Conclusion: These results in people with insomnia corroborate prior reports of increased high-frequency sleep EEG power associated with mindfulness training. This change in beta EEG pattern merits further evaluation as a potential marker of the effects of mindfulness meditation on sleep, especially given the paradoxical findings in the context of insomnia.

Clinical Trial Registration: clinicaltrials.gov, NCT00768781.