Background and purpose-A growing body of evidence suggests that sleep plays an essential role in the consolidation of different memory systems, but less is known about the beneficial effect of sleep on relational memory processes and the recognition of emotional facial expressions, however, it is a fundamental cognitive skill in human everyday life. Thus, the study aims to investigate the effect of timing of learning and the role of sleep in relational memory processes. Methods-84 young adults (average age: 22.36 (SD: 3.22), 21 male/63 female) participated in our study, divided into two groups: evening group and morning group indicating the time of learning. We used the face-name task to measure relational memory and facial expression recognition. There were two sessions for both groups: the immediate testing phase and the delayed retesting phase, separated by 24 hours. Results-We failed to find differences neither between the groups nor in the general performance (number of correct answers independent of the emotional valence of facial expression) neither different emotional facial expressions in both sessions. In contrast, the within-subject analyses revealed to us that the morning group showed higher forgetting rates in the long term testing phase compared to the short term retest while the evening group showed similar performance in both retest phases. Moreover, we found a correlation between performance and sleep quality, sleep latency and sleep efficiency. Conclusion-Our results suggest that the timing of learning and sleep plays an important role in the stabilizing process of memory representation to resist against forgetting.