Abstract
Background: Among the multiple functions of sleep, its role in the establishment of memories seems to be particularly important. Spontaneous memory reactivation during sleep can promote consolidation and thus shape the memory storehouse that each individual possesses. Targeted memory reactivation (TMR) is a method whereby cues associated with previous learning are used to externally reactivate aspects of learning.

Aims and Objectives: The aim of this study was to evaluate the effect of TMR by Indian classical music and Vedic Chants during daytime nap on consolidation of newly learnt material and to evaluate effect of time spent in various stages of sleep during TMR on consolidation of newly learnt material.

Materials and Methods: The study was conducted on 45 participants who were divided into three groups. Memory was assessed with the help of digit span (working memory) and paired associate task (long-term memory) before and after the nap. During 1 h daytime nap, sleep was monitored by polysomnograph. Sound cues were played both during learning of word pairs and during sleep.

Results: Participants listening to Vedic Chant performed better in digit span after nap (P = 0.001). When evaluated for subjects of all groups significant positive correlation was found between improvements in digit span score after nap and sleep efficiency, time spent in N3, and percentage of N3 in total recording time and had negative correlation with awake time. No significant change in score of paired associate task after nap was seen.

Conclusion: This result paves way for usage of Vedic Chants as a background sound during daytime nap to improve working memory. The result also suggests that a daytime nap with good sleep efficiency and presence of N3 stage of sleep can increase the work efficiency of individuals after nap. Improvement in score of paired associate task in Vedic Chants group though not statistically significant demands for further research in the effect of Vedic Chants on long-term memory.

Key words: Daytime Nap; Memory; Targeted Memory Reactivation; Vedic Chant; Indian Classical Music