FLUNITRAZEPAM EFFECTS ON HUMAN SLEEP EEG SPECTRA .2. SIGMA-ALTERATIONAND BETA-ALTERATION DURING NREM SLEEP

Flunitrazepam (FNZ) is known to enhance the higher EEG frequencies, in cluding sigma (10-15 Hz) and beta (20-28 Hz). Both sigma and beta freq uency bands show an inverse relationship with delta (0.3-3 Hz) during NREM periods, as we have previously reported. It is not known whether generation of these two EEG frequencies is mediated by the same or dif ferent neuronal mechanisms. In this report, we compare alterations of delta, sigma and beta EEG induced by FNZ (4 mg) orally administered to five healthy male subjects for seven consecutive nights. Sleep EEG on the baseline night (BLN), and the fourth and seventh drug nights (4DN , 7DN) was subjected to fast Fourier transform (FFT) analysis. On drug nights, sigma was enhanced without regard to delta amount, but beta w as enhanced only during epochs containing low delta. Thus, sigma and b eta EEG were altered differently by the same pharmacological agent. Th ese results suggest that sigma and beta EEG are mediated by different neuronal mechanisms.