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

Abstract

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 × 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.