Effects of zopiclone on polysomnography and daytime EEG - vigilance controlled EEG and resting EEG

Correlation between the effects of Zopiclone (ZPC) on sleep polysomnograms (PSG) and on daytime EEGs (vigilance controlled EEG and resting EEG) were examined on 12 healthy adult male volunteers. PSGs were recorded after single an oral administration of 10 mg ZPC or placebo, according to the double-blind cross-over method. Daytime EEGs were recorded after the single oral administration of 7.5 mg ZPC or placebo, and recorded with eye closed for 3 min with vigilance controlled at rest, respectively. Then, square roots of the absolute power of the delta, theta, alpha, and beta activities were calculated. ZPC decreased the percentage of stage 1 sleep, while it increased the percentage of stage 2 total sleep time, and time of slow-wave sleep in the Ist and 2nd sleep cycles (SWS 1 & 2). The delta activity increased, the alpha decreased in vigilance controlled EEG, the theta decreased, and the beta increased in both vigilance EEGs. Although the parameters of PSG had no specific correlations with the changes of vigilance controlled EEG, the changes in SWS 1 & 2 correlated positively with the changes of the delta activity in daytime resting EEG. This indicates that the increase of slow-wave sleep due to ZPC could be related to the increase of the delta activity in the daytime resting EEG.