Quantitative EEG studies of primary insomnia (PI) suggest that increased high frequency and reduction in slow frequency EEG activity could be associated with cortical "hyperarousal" and sleep homeostasis dysregulation. This preliminary study is the first to apply higher order EEG analysis in chronic PI patients. We analyzed phase coupling in two patients against two control subjects. We defined an index of resonant frequency (IRF) and show that both patients were characterized by high IRF values that suggest an increase in local cortical information processing before treatment. We show that cognitive behavioral therapy for insomnia (CBT-T) is able to reverse EEG phase coupling towards control values in as little as eight sessions. After treatment the patients were characterized by lower index values, thus suggesting recovery of information processing over wide-spread cortical areas.