WAKING ELECTROENCEPHALOGRAM ACTIVITY AS A CONSEQUENCE OF SLEEP AND TOTAL SLEEP-DEPRIVATION IN THE RAT

Effects of 6 hours of total sleep deprivation (TSD) by gentle handling and 6 hours of sleep on the waking electroencephalogram (EEG) activit y of 14 Wistar rats were studied during the lights-on portion of the l ight-dark cycle under two TSD schedules: a) TSD 0800-1400 hours and sl eep 1400-2000 hours, and b) sleep 0800-1400 hours and TSD 1400-2000 ho urs. EEG was recorded monopolarly from left and right parietals referr ed to ipsilateral reference electrodes. Spectral analysis was performe d on samples of waking EEG during TSD (each 30 minutes) and during sle ep (each 60 minutes after enforced awakening). The following significa nt changes were observed: TSD induced a linear increase in the absolut e power of delta (1.46-3.42 Hz) and the full band (1.6-24.9 Hz) and pr oduced a decrease in the interparietal correlation of theta. Sleep ind uced the opposite results. Theta relative power (power in a band expre ssed as a percentage of total power between 1.46 and 24.9 Hz) showed a circadian effect. It was higher at 1400 hours than at 0800 and 2000 h ours after both sleep and TSD conditions. Six hours of TSD were enough to induce significant changes in the waking EEG regardless of positio n of TSD in the lights-on period of the light-dark cycle.