Sleep regulation involves a homeostatic process, as NREM sleep amount and intensity (slow-wave activity, SWA) are proportional to the duration of prior wakefulness. A standard method for investigating this sleep-regulatory process is restricting sleep and then measuring the resulting changes in NREM amount and intensity. Here, we used a six-hour sleep restriction paradigm both before and after 10 days of social-defeat stress to investigate the sleep-regulatory differences between resilient and susceptible mice (A). Prior to social-defeat stress exposure, mice later identified as susceptible showed increased sleep-recovery to six-hours of sleep restriction (B; C, top row) when compared to mice identified as resilient (B; C, top row). This pattern was present for both NREM and REM sleep (C, top row). Susceptible and resilient mice lost similar amounts of NREM and REM sleep during sleep-restriction (C, bottom row) and the increased recovery response for susceptible mice persisted when NREM sleep recovered was normalized to the amount of sleep lost (C, bottom). After social-defeat stress, susceptible animals continued to show increased NREM-sleep recovery, but not REM-sleep recovery (D, top row). Sleep intensity (NREM slow-wave activity, SWA) was higher in susceptible animals prior to social-defeat stress during both baseline and following sleep restriction (E, G). This increased sleep intensity in susceptible mice persisted and was more prominent after social-defeat stress (F, H). (B) X indicates interaction ratios between 0.9 and 1.1 that were excluded from sleep analysis. (C) Total sleep: repeated measures ANOVA main effect of time (MET)—F(8, 80)=53.78, p<0.0001; main effect of susceptibility (MES)—F(1, 10)=2.05, p=0.18; interaction (IST)—F (8, 80)=5.14, p<0.0001. NREM sleep, MET—F(8, 80)=50.75, p<0.0001; MES—F(1, 10)=1.92, p=0.19; IST—F (8, 80)=4.77, p<0.0001. REM sleep, MET—F(8, 80)=36.88, p<0.0001; MES—F(1, 10)=2.73, p=0.13; IST—F (8, 80)=3.32, p<0.0025. Sleep lost, Student’s paired t, NREM—t(7)=0.99, p=0.36; REM—t(7)=0.92, p=0.37. % recovered: MET—F(8, 80)=41.45, p<0.0001; MES—F(1, 10)=1.58, p=0.24; IST—F (8, 80)=3.27, p=0.0029. (D) NREM sleep: MET—F(8, 56)=49.2, p<0.0001; MES—F(1, 7)=3.96, p=0.049; IST—F (8, 56)=1.86, p=0.23. REM sleep: MET—F(8, 56)=24.58, p<0.0001; MES—F(1, 7)=0.02, p=0.87; IST—F (8, 56)=0.48, p=0.86. (E) Baseline, parietal: MES—F(1, 95)=4.21, p=0.043. (F) Frontal baseline: IST—F(11, 75)=2.13, p=0.028; frontal sleep restriction, IST—F(8, 63)=2.13, p=0.028; parietal sleep restriction, IST—F(8, 63)=2.84, p=0.009. *=p ≤ 0.05, Holms Sidak’s multiple comparison; n=13. Data points represent mean ± SEM with the exception of panel B which presents median, 25th to 75th percentiles and min/max values.