Beta/Gamma EEG activity in patients with primary and secondary insomnia and good sleeper controls.
OBJECTIVE
Several studies have shown that patients with insomnia exhibit elevated levels of Beta EEG activity (14-35 Hz) at or around sleep onset and during NREM sleep. In this study, we evaluated 1) the extent to which 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 which high frequency EEG activity occurs in patients with primary, as opposed to secondary, insomnia.


METHODS
Three groups (n=9 per group) were compared: Primary Insomnia, Insomnia secondary to Major Depression, and Good Sleeper Controls. Groups were matched for age, sex and body mass. Average spectral profiles were created for each NREM cycle after removing waking and movement epochs and epochs containing micro- or mini-arousals.


METHODS
Sleep Research Laboratory


METHODS
Patients with primary and secondary insomnia


METHODS
N/A.


RESULTS
Subjects with Primary Insomnia exhibited more average NREM activity for Beta-1 (14-20Hz), Beta-2 (20-35Hz) and Gamma activity (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 tending to exhibit more activity than the other groups. Correlational analyses revealed that average NREM Beta-1 and Beta-2 activity tended to be negatively correlated with subjective-objective discrepancy measures for total sleep 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 patients with Primary Insomnia is limited to the Beta/Gamma range (14-45 Hz), and is negatively associated with the perception of sleep.
Perlis
M L
ML
Department of Psychiatry, University of Rochester, NY 14642, USA. Michael_Perlis@URMC.Rochester.edu
Smith
M T
MT
Andrews
P J
PJ
Orff
H
H
Giles
D E
DE
D000328:Adult; D001611:Beta Rhythm; D003865:Major Depressive Disorder / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000209:etiology*; D012895:Sleep, REM / Q000502:physiology*; D013997:Time Factors