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Published on: August 2, 2017
EEG spectral analysis in primary insomnia: NREM period effects and sex differences
Daniel J Buysse1, Anne Germain, Martica L Hall
1Neuroscience Clinical and Translational Research Center and Sleep Medicine Institute, University ofPittsburgh School ofMedicine, Pittsburgh, PA, USA. buyssedj@upmc.edu
Study Objectives:
To compare NREM EEG power in primary insomnia (PI) and good sleeper controls (GSC), examining both sex and NREM period effects; to examine relationships between EEG power, clinical characteristics, and self-reports of sleep.
Design:
Overnight polysomnographic study.
Setting:
Sleep laboratory.
Participants:
PI (n=48; 29 women) and GSC (n=25; 15 women).
Interventions:
None.
Measurements:
EEG power from 1-50 Hz was computed for artifact-free sleep epochs across four NREM periods. Repeated measures mixed effect models contrasted differences between groups, EEG frequency bands, and NREM periods. EEG power-frequency curves were modeled using regressions with fixed knot splines.
Results:
Mixed models showed no significant group (PI vs. GSC) differences; marginal sex differences (delta and theta bands); significant differences across NREM periods; and group*sex and group*NREM period interactions, particularly in beta and gamma bands. Modeled power-frequency curves showed no group difference in whole-night NREM, but PI had higher power than GSC from 18-40 Hz in the first NREM period. Among women, PI had higher 16 to 44-Hz power than GSC in the first 3 NREM periods, and higher 3 to 5-Hz power across all NREM periods. PI and GSC men showed no consistent differences in EEG power. High-frequency EEG power was not related to clinical or subjective sleep ratings in PI.
Conclusions:
Women with PI, but not men, showed increased high-frequency and low-frequency EEG activity during NREM sleep compared to GSC, particularly in early NREM periods. Sex and NREM period may moderate quantitative EEG differences between PI and GSC.
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