[The effect of zolpidem on EEG activity in falling asleep process]. / Wplyw zolpidemu na czynnosc EEG w procesie zasypiania.

The effect of zolpidem on the brain bioelectric activity in falling asleep process of 13 healthy volunteers (8 women, 5 men), aged 20-24 years, was investigated. Its effect on sleep latency was studied. Quantitative analysis of sleep spindles occurrence was realized. It caused significant increase of sleep spindles activity in the first hour after its application (p < 0.001) and had influence on reduction of sleep latency in comparison with placebo. Our findings confirm the hypnotic effect of zolpidem.

Effect of lateral hypothalamic lesion on sleep-waking pattern and EEG power spectra in the rat.

Bilateral, electrolytic lesion of the lateral hypothalamus (LH) in rats produces hyposomnia and qualitative EEG changes which are difficult to assess by conventional visual inspections of electroencephalograms. In the present study the spectral analysis of EEG was applied in LH-lesioned rats and confronted with a standard visual scoring method. One-hour samples of hippocampal and cortical EEG were taken from the light part of the circadian cycle before and after electrolytic or sham LH damage. In half of the LH-lesioned rats a power spectral analysis was performed using a Fast Fourier Transform routine at 1 Hz bands from 0.5 to 25 Hz; in the other half, as well as in the sham-lesioned group, EEG records were visually scored for the amount of waking, slow wave sleep and paradoxical sleep. Significant hyposomnia effects were found in LH-lesioned rats. Power spectral analysis of hippocampal EEG revealed a significant increase in power density at 4-6 Hz and a reduction at 7-10, 14-17, 19-22 and 23-24 Hz. In neocortical EEG there was a significant increase in power density at 5-6 Hz band and a reduction at 7-8 Hz. The results are discussed in the context of the effects of selective destruction of the specific neurotransmitter systems occupying the LH area.

Spectral analysis in cyclic changes of human sleep evaluation.

In this study cyclic changes of human sleep structure were examined. For whole-night polysomnograms of 35 healthy volunteers of both sexes, manual hypnograms were created and divided into NREM-REM cycles. EEG signals from C3-A2 derivation were analysed by computer using a Fast Fourier Transform (FFT). For consecutive NREM-REM cycles of individual sleep stages, EEG power density contents for delta, theta, alpha, sigma and beta waves were analysed. For consecutive sleep cycles, a clear decrease in NREM sleep duration, especially slow wave sleep duration, was obtained. In addition, a decrease in power density of delta waves was observed. For consecutive sleep cycles, increases in REM sleep duration and in power density of theta and alpha waves were obtained. In consecutive sleep cycles, high amplitude delta slow waves are replaced by higher frequency and lower amplitude waves. Thus stages of NREM sleep are replaced by stages of REM.