Positive Effects of Sleep on Memory Consolidation and Learning New English Words in Persian Language Speakers

Background and Objective The role of night sleep in learning and consolidating memory has been mentioned and researched in many studies. Different tools have been used to determine the effect of sleep. However, this kind of research in the Iranian population is limited. Thus, the objective of this study was to determine the role of sleep in immediate and late learning of new words of second language in a number of English language learners.Methods Forty Persian males aged 18–35 years old participated in our study in two groups. The first group completed learning steps at 8–10 AM and repeated the test after 12 hours. The second group performed the initial stages of learning at 8–10 PM and repeated the test next morning. Everyone completed the Pittsburgh Sleep Quality Index Persian version for evaluating their sleep habits during last month and the effect of their sleep habits on achieved task scores.Results Comparison of the number of recalled words (NRW) between the two groups showed a significant difference (p-value < 0.001) with better performance in night group. The NRW during the second stage was positively influenced by better subjective sleep quality, lower sleep latency, higher sleep efficiency, and more sleep duration significantly (p-value < 0.05). There was no significant relationship of NRW with sleep disorders, sleep medications, or daytime dysfunction.Conclusions Adequate night sleep could improve late learning of second language in our research subjects. Sleep quality, latency in falling asleep, and subjective sleep quality might play a role in this learning process.