Paradoxical Sleep Deprivation (PSD) induces oxidative stress and interferes permanent memory consolidation in hippocampus. Purwoceng (Pimpinella prutjan Molken) is herbal medicine with antioxidant effect. These effects will be more effective with nanosuspension technology. The research purposes is to find effect of PSD to rats’ spatial memory reduction and to find purwoceng nanosuspension extract effect to improve rats’ spatial memory after PSD stress induction. The research method is randomized controlled trial with posttest only with control group approach to 36 white male albino rats Wistar strain which is induced by 96 hours PSD stress model. Experiment groups is regular extract 25 mg/300g BW/day, purwoceng nanosuspension extract 25 mg/300 gBW/day, 50 mg/300 gBW/day, and 75 mg/300 gBW/day. Statistical analysis found that there is no significant effect of purwoceng extract to memory traveling time (p=0,414) and memory track length (p=0,316) between pre-PSD and post-PSD group. There is significant effect of PSD stress after purwoceng administration to memory track length and memory travelling time (p=0,005). The conclusion is that there is significant correlation between the difference of memory latency and memory traveling time of MWM test between the various purwoceng nanoemulsion dose. The 25-50 mg/300 gBW/day is effective dose of purwoceng nanoemulsion extract to repairs spatial memory degeneration after PSD stress.