Waking EEG in primary insomnia.

Quantitative analysis of the waking EEG has been proposed as an objective method for measuring neurobehavioral impairment in primary insomnia. Thirty six patients with DSM-IV primary insomnia diagnosis (mean age 36 years) and 29 controls, matched for age and education, participated in the study. Waking EEG from 21 scalp electrodes was subjected to spectral analyses using a fast Fourier transform algorithm. Significantly lower values of power in the theta range and higher values of beta power were found in insomniacs as compared to control subjects. This theta power decrease in patients suffering from insomnia was not uniform throughout the brain, but it was pronounced in prefrontal derivations. Lower values of theta power correlated negatively and higher values of beta power correlated postively with Hyperarousal Scale score. Results of the research presented here support the notion of twenty-four hour hyperarousal in primary insomnia. Attenuated theta and enhanced beta power can be electrophysiological correlates of dysfunctional arousal in insomnia. Less waking theta power in insomniacs suggests a decrease in homeostatic sleep propensity.