Sojourn times and normalized transition rates in the onset phase (0-2000 s; ca. first 30 min). The estimated mean of the average time spent between two jumps (sojourn time; s) in A) WAKE and B) SLEEP, and the normalized transition rates (relative rates compared to the transition rate of HC-VEH group, which is 1) C) from WAKE to SLEEP and D) from SLEEP to WAKE states. Each point (●) represents the mean values and the line segments show the 95% confidence interval surrounding them. Groups: home cage-chronic vehicle treatment (HC-VEH); home cage-chronic escitalopram treatment (HC-SSRI); REM sleep deprivation-chronic vehicle treatment (RD-VEH); REM sleep deprivation-chronic escitalopram treatment (RD-SSRI).