Fig. 2: Respiration modulates sleep rhythms.
From: Respiration modulates sleep oscillations and memory reactivation in humans
a Time–frequency representation of NREM sleep EEG data locked to inhalation peaks, contrasted against random data segments (mean z values across significant electrodes). Contours indicate significant clusters (two-sided dependent-sample t test; P < 0.001, corrected), illustrating enhanced power in the SO_spindle range around inhalation peaks (time = 0). The black line on the left illustrates mean z power, averaged across time in the cluster (±SEM across participants). The white waveform depicts the inhalation-locked respiration signal (mean ± SEM across participants). The topography illustrates the statistical results across electrodes. b Source data suggest that TFR results emerge from frontoparietal and right medial temporal lobe areas (P = 0.037, corrected). c The modulation index indicates that the respiration phase influences EEG amplitudes at electrode F2 (mean ± SEM across participants) with peaks in the SO (0.5 Hz) and spindle range (15.5 Hz; z > 1.96; the red line depicts significantly modulated frequencies; corrected). d SO downstates (red) and spindle onsets (blue) were non-uniformly distributed across participants in relation to the respiratory phase (two-sided V- test; SOs: Vmean = 7.42 ± 0.28, all P < 0.05; Spindles: Vmean = 6.84 ± 0.24, all P < 0.05; corrected using FDR32; contour lines encompass significant electrodes). The circular plot illustrates the preferred respiration phases for SO (red, electrode F2: mean angle = −21.36° ± 0.20, mean vector length = 0.58) and spindle modulation (blue, electrode P1: mean angle = 14.06° ± 0.23, mean vector length = 0.44; inhalation peak = 0°). The right panel illustrates the temporal modulation of SOs (red, electrode F2) and spindles (blue, electrode P1; event percentage in relation to inhalation peaks ± 1.5 s; mean ± SEM across participants) by respiration. Solid horizontal lines indicate significant differences from event-free segments (SOs: p = 0.004; Spindles: P = 0.002; corrected). e The phase-slope index (PSI; mean ± SEM across participants), indicates that respiration phases predict both SO and spindle amplitudes (t tests against zero, two-sided; SOs (red): t1,19 = 2.17; P = 0.042; Spindles (blue): t1,19 = 3.1; P = 0.005). Source data are provided as a Source Data file.
