A STUDY ON THE IMPACT OF DAYTIME NAP ON DECLARATIVE MEMORY IN YOUNG ADULTS
Objective: To evaluate the impact of the daytime nap on declarative memory assessed by performance of memory tasks in young adults.
Methods: The study was carried out among 30 subjects, 15 males and 15 females divided into daytime napping group and control group. These
subjects were allowed for 60 minutes retention interval. Later the subjects in daytime nap group were put to bed in a sound attenuated sleep
chambers to enable napping while control group was kept awake. Performance of declarative memory was evaluated both pre and post intervention
for all subjects by three tests namely, unrelated paired associates, maze learning, and the Reyâ€“Osterrieth complex figure.
Results: Statistical analysis revealed that independent t-value was significant between napping and awake group on memory task performance
conducted before and after 60 minutes retention interval (p<0.001). Sleep parameters analysis in napping group show sleep onset latency time
of 10.6 minutes, which was dominated by Stage I sleep with sleep efficiency of 56.35%. Total sleep time was 51.46 minutes in napping group.
Improvement in memory task was statistically significant as the results of unrelated word pairâ€™s associates the performance of nap group was 97.2%
when compared with the control group with 90% performance. Reyâ€“Osterrieth complex figure test results show the average time taken by nap group
was 45 seconds, and that of awake group was 63 seconds. In the case of maze learning task, the time taken by nap group was 27.33 seconds and by
awake group was 38.2 seconds (p<0.001).
Conclusion: From the results it is evident that non declarative memory is well enhanced by daytime napping shown by improved performance tests.
This might be brought about by memory consolidation process triggered during sleep onset latency.
Keywords: Daytime nap, Non-rapid eye movement sleep, Memory consolidation, Declarative memory task.
2. Ferrie JE, Shipley MJ. A prospective study of change in sleep duration: associations with mortality in the Whitehall II cohort .sleep J:2007:30(12):1659-66.
3. Fischer S, Gais S. Implicit learningâ€“explicit knowing: a role for sleep in memory system Interaction. Journal of cognitive neuroscience 2006;18:311-19.
4. Alger SE, Lau H, Fishbein W. Delayed onset of a daytime nap facilitates retention of declarative memory. PLoS one 2010; 5(8)e12131.
5. Wagner U, Gais S, Hilde H, Verkge R, Born J. Sleep inspires insight. Nature 2004;352-355
6. Yotsumoto Y, Watanabe T, Sasaki Y. Different dynamics of performance and brain activation in the time course of perceptual learning. Neuron 2008;2757(6):827-33
7. Tucker M, Hirota Y, Wamsley EJ, Fishbein HW. Neurobiology of learning and memory 2006; 86(2)241-247
8. Baddeley A, Wilson BA. Prose recall and amnesia: Implications for the structure of working memory. Neuropsychologia 2002:40(10):1737-1743
9. Gais S, Albouy G, Boly M, Dang V, Darsand A, Desseilles M. et. al. Sleep transforms the celebral cortex trace of declarative memories. Proc Natl Acad Sci USA 2007(104):18778-18783
10. Hennevin E, Huetz C, Edeline JM, Neural representations during sleep; from sensory processing to memory traces. Neurobiology of learning and memory 2007;87(3):416-440
11. Fisher S, Hallschmid M, Elsner A, Born J. Sleep forms memory for finger skills. Proc Natcl Acad Science 2002;(99):11987-11991
12. Gais S, Plihal W, Wagnes U, Born J. Early sleep triggers memory for early visual discrimination skills. Nat Neurosci 2000;(3):1335-1329
13. Fennk M, Nusbaum HC, Margoliash D. Consolidation during sleep of perceptual learning of spoken language 2003: Nature;(425):614-616
14. Mednick SC, Cai DJ, Kanaday J, Drummond SP. Comparing the benefits of caffeine, naps and placebo on verbal, motor and perceptual memory. Behavioral Brain Research 2008;93(1):79-86
15. Macquet P. The role of sleep in learning and memory. Science 2001;(294):1048-1052.
The publication is licensed under CC By and is open access. Copyright is with author and allowed to retain publishing rights without restrictions.