Daytime Napping and Associative-Memory Retrieval Speed: An Exploratory Behavioral and EEG Study

Purpose: To test whether a daytime nap was associated with improved associative-recognition performance relative to monitored wakefulness and to determine where any response-time (RT) difference occurred in the RT distribution. Methods: Fifteen healthy students completed nap and wake sessions in a within-participant design. Each session included word-pair learning, immediate recognition, a 60-min interval, and delayed recognition without additional study. Trial-level log RT was the focal outcome; accuracy and electroencephalography (EEG) were complementary outcomes. Results: The RT Condition-by-Time interaction was significant (b = -0.063, 95% CI [-0.117, -0.009], p = .027). Responses were 6.7% faster after the nap (p = .010) but did not change after wakefulness (p = .704), with the difference concentrated among slower responses. Accuracy showed no condition-specific change (p = .401). Nap EEG showed aperiodic spectral slowing and stronger periodic sigma activity, but no EEG measure explained the RT effect. Conclusions: Daytime napping was associated with faster delayed associative recognition, primarily through attenuation of the slowest responses. The exploratory findings warrant larger confirmatory studies.