Figure 5

EEG power spectrum and SWA during recovery sleep. A. Time course of EEG power spectrum in drowsiness, SWS and the two states combined for the first three 2-hour intervals of recovery sleep. For each frequency bin (0.25 Hz) curves connect means (± SEM, n = 6) of relative power density expressed as percentage of mean values in that bin over the baseline dark period in the corresponding vigilance state. Horizontal bars depict frequency bins where the EEG power during recovery was significantly different from that during the corresponding baseline interval (p < 0.05, paired t-test). B. Time course of SWA (0.5–4 Hz) in drowsiness, SWS sleep and the two states combined. For each vigilance state, the 2-hour values are expressed as percentage of mean SWA during the baseline dark period in the corresponding vigilance state. Triangles depict significant difference between SWA during recovery sleep relative to the same circadian time during baseline sleep. Note that SWA in SWS and in NREM sleep (SWS + drowsiness) at the beginning of recovery sleep shows a trend to be higher (SWS, p = 0.08; NREM sleep, p = 0.05, paired t-test) than at the beginning of baseline sleep. C. Time course of SWA (0.5–4 Hz) in drowsiness, SWS sleep and the two states combined during the first 2 hours after sleep onset in baseline sleep and recovery sleep. For each vigilance state, values are expressed as percent of mean SWA during baseline for the corresponding vigilance state. Each data point represents mean (± SEM, n = 6) SWA over consecutive 10-min intervals. Triangles depict significant differences between SWA during recovery sleep relative to baseline sleep (p < 0.05, paired t-test). Inset depicts mean values (± SEM, n = 6) of peak SWA during the first 2 hours of baseline and recovery sleep analyzed over 30-min intervals. Asterisks indicate significant difference between baseline and recovery sleep (p < 0.05, paired t-test).