Beta/Gamma EEG activity in patients with primary and secondary insomnia and good sleeper controls

Study Objective: Several studies have shown that patients with insomnia exh ibit elevated levels of Beta EEG activity (14-35 Hz) at or around sleep ons et and during NREM sleep. In this study, we evaluated 1) the extent to whic h high frequency EEG activity is limited to the 14-32 Hz domain, 2) whether high frequency EEG activity (HFA) is associated with discrepancies between subjective and PSG measures of sleep continuity, and 3) the extent to whic h high frequency EEG activity occurs in patients with primary, as opposed t o secondary, insomnia. Design: Three groups (n=9 per group) were compared: Primary Insomnia, Insom nia secondary to Major Depression, and Good Sleeper Controls. Groups were m atched for age, sex and body mass. Average spectral profiles were created f or each NREM cycle after removing waking and movement epochs and epochs con taining micro- or mini-arousals. Setting: Sleep Research Laboratory Patients or Participants: Patients with primary and secondary insomnia Interventions: N/A Measurements and Results: Subjects with Primary insomnia exhibited more ave rage NREM activity for Beta-1 (14-20Hz), Beta-2 (20-35Hz) and Gamma activit y (35-45Hz) than the other two groups (p.<.01). Group differences were also suggestive for Omega activity (45.0-125Hz) (p.<.10), with MDD subjects ten ding to exhibit more activity than the other groups. Correlational analyses revealed that average NREM Beta-1 and Beta-2 activity tended to be negativ ely correlated with subjective-objective discrepancy measures for total sle ep time and sleep latency. Conclusions: Our results confirm that Beta activity is increased in Primary Insomnia. In addition, our data suggest that high frequency activity in pa tients with Primary Insomnia is limited to the Beta/Gamma range (14-45 Hz), and is negatively associated with the perception of sleep.