Analysis of sleep EEGs by the interval histogram method: Validity of the baseline night as a control and the effect of ethyl loflazepate (CM6912)

Abstract

The effects of an anxiolytic drug, ethyl loflazepate (CM6912) on sleep EEGs were investigated by the interval histogram method originally developed. EEGs were classified into each of the δ2-β2 and σ1 wave-form parameters, and the individual frequencies were determined on the third baseline, second drug and the first recovery nights in each sleep stage. In comparison with the second baseline night, the σ1 waves in stage 2 sleep and the δ1 waves in REM sleep were decreased and the α and σ1 waves in stage 3 sleep were increased on the third baseline night. In consideration of the 5% significance level and the remarkable influence of drug administration, described below, no major problems were encountered in the use of the night as a control in this experimental schedule. The main characteristics of administration of CM6912 manifested as decreases in the slow wave, increases in the fast wave, and an increase in the σ1 wave in sleep stages other than stage 1. These tendencies were remarkable on the second drug night and were still evident even on the recovery night. Increases in σ1 wave were related to increases in sleep spindles. The increases in the β2 wave were particularly remarkable in REM sleep.