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

•NREM EEG beta (16–25 Hz) power during sleep increased following mindfulness-based interventions.•Pre-treatment, this NREM EEG activity was not associated with mindfulness or insomnia.•Post-treatment, NREM EEG beta power was positively associated with mindfulness and negatively associated with insomnia.