(A) Comparison of task proficiency between sleep-first and wake-first groups after the sleep retention interval (mean ± standard error of the mean [SEM]). Adolescents in the wake-first group had higher task proficiency given the additional juggling performance test, which also reflects additional training (t(23) = −2.24, p = 0.034). (B) Comparison of slow oscillation (SO)–spindle coupling strength in the adolescent sleep-first (blue) and wake-first (green) groups using cluster-based random permutation testing (Monte-Carlo method, cluster alpha 0.05, max size criterion, 1000 iterations, critical alpha level 0.05, two-sided). Left: exemplary depiction of coupling strength at electrode C4 (mean ± SEM). Right: z-transformed t-values plotted for all electrodes obtained from the cluster test. No significant clusters emerged. (C) Left: cluster-corrected correlations between individual coupling strength and overnight task proficiency change (post–preretention) for adolescents of the sleep-first group with Spearman correlation at C4, uncorrected. Asterisks indicate cluster-corrected two-sided p < 0.05. Gray-shaded area indicates 95% confidence intervals of the robust trend line. Participants with a more precise SO–spindle coordination show improved task proficiency after sleep. Right: cluster-corrected correlation of coupling strength and overnight task proficiency change for adults. Independently, adolescents and adults with higher coupling strength have better task proficiency after sleep. (D) Left: cluster-corrected correlation of coupling strength and overnight learning curve change for adolescents. Same conventions as in (C). Higher coupling strength related to a flatter learning curve after sleep. Right: cluster-corrected correlation of coupling strength and overnight learning curve change for adults. Higher coupling strength related to a flatter learning curve after sleep in both age groups. (E) Cluster-corrected correlations for coupling strength of co-occurrence corrected events in NREM2 and NREM3 sleep with overnight task proficiency change (top) and overnight learning curve change (bottom). Asterisks indicate cluster-corrected two-sided p < 0.05. Similar to our original analyses (Figure 3D, E) we found significant cluster-corrected correlations at C4. (F) Cluster-corrected correlations between individual coupling strength and overnight task proficiency change (post–preretention) after outlier removal with Spearman correlation at C4, uncorrected. Similar to our original analyses we found a significant central cluster (mean rho = 0.35, p = 0.029, cluster-corrected) after outlier removal. (G) Same conventions as in (F) but for overnight learning curve change. Similar to our original analyses we found a significant correlation at C4 (rho = −0.44, p = 0.047, cluster-corrected). (H) Topographical plot of Spearman rank correlations of coupling strength in the adaptation night and learning night across all subjects. Overall coupling strength was highly correlated between the two measurements (mean rho across all channels = 0.55), supporting the notion that coupling strength remains rather stable within the individual (i.e., trait). (I) To investigate a possible state effect for coupling strength and motor learning, we calculated the difference in coupling strength between the two nights (learning night–adaptation night) and correlated these values with the overnight change in task proficiency and learning curve. We identified no significant correlations with a learning-induced coupling strength change. Neither for task proficiency (top) nor learning curve change (bottom).