Sleep-wake Variables Research Articles

Sleep-wake variables and EEG power spectra in Mongolian gerbils and Wistar rats

Using electroencephalographic methods (EEG), we have analyzed the basal sleep structure and the EEG power spectra of gerbils and rats during periods of wakefulness (W), synchronized sleep (SS) and paradoxical sleep (PS). During the 6hr light period examined, duration of sleep was similar for rats and gerbils, but gerbils showed fewer PS episodes and a longer amount of SS episodes followed by wakefulness. In addition, SS episodes preceding PS were of longer duration in gerbils than in rats. EEG power spectral analysis indicated a higher relative output in the 1–4 Hz range in gerbils in comparison with rats. On the whole, the data indicate the existence of significant differences in the basal sleep structure and EEG power spectra of gerbils and rats. This background information might be useful in the comparison of the effects of a given experimental treatment, such as cerebral ischemia, on the EEG activity of these two animal species.

Developmental course of nighttime sleep-wake patterns in full-term and premature infants during the first year of life. I.

Two groups of infants (40 normal full-term, 24 prematurely born infants) were matched on conceptional age and were studied at seven ages during the first year of life. All-night time-lapse video somnography was obtained n the home at 2, 4, 8, 20, 24, 36, and 52 weeks of age. The developmental course of sleep-wake state proportions, sleep onset indices, and special variables assessing temporal organization are compared. Age-appropriate developmental norms for sleep-wake state assessment during the first year of life are presented, using video somnography. In general, sleep-wake state ontogenesis is comparable in the two groups. The premature group is more variable from one age to the next, even though both groups demonstrate significant individual stability of some sleep-wake variables over the first year of life.

EEG spindle activity as a function of age: Relationship to sleep continuity

This study assessed sleep spindle activity and its relationship to transient EEG activation in young adult and aged cats. Sleep-wake variables were monitored polygraphically for 12 h in 5 young adult (2–4 years) and five aged (9–11 years) animals. Recordings were scored for behavioral state. Then, using bandpass frequency analysis, sensorimotor cortical spindles were evaluated in three, 5-min segments of the NREM sleep EEG. Both the incidence of transient arousals (TA) and spindle(≥ 25 μV) densities were significantly higher in the aged animals than in the young adults. In the young animals only, spindle densities reliably predicted the incidence of TAs. We suggest that spindle expression varies in relation to ascending reticular activating system tone, constituting a functionally-inhibitory thalamocortical response to neurophysiological conditions which promote central activation.