Sleep-like slow waves. a, Slow-wave density (wave/min averaged across all electrodes) per treatment. The raincloud plot for each drug treatment [placebo PLA: gray (N = 32), methylphenidate MPH: orange (N = 32), atomoxetine ATM: purple (N = 31), citalopram CIT: green (N = 31)] is shown in the left panel. Stars denote the significance level (ns: nonsignificant, *p < 0.05, **p < 0.01, ***p < 0.001) of the difference between placebo and the three treatments used in this protocol (MPH vs PLA, ATM vs PLA, CIT vs PLA), as determined by linear mixed-effect models. In the right panel, slow-wave density split by treatment and block (N = 10 blocks) showing the sample average (circle) and SEM (colored areas) across participants is shown. A nonsignificant interaction (ns) between block number and drug treatment was found, as determined by linear mixed-effect models (see Materials and Methods). b, Topographical maps of slow-wave density for each drug treatment. c, Topographical maps of the statistical differences in slow-wave density between MPH and PLA (left), ATM and PLA (middle), and CIT and PLA (right). The t values obtained with mixed-effect models for each electrode are shown (see Materials and Methods). Significant clusters of electrodes (p_cluster < 0.05) are shown with black dots (cluster-permutation approach; see Materials and Methods).