Comment in:

Sleep. 2008 Feb 1;31(2):163-4.

Enhancement of declarative memory performance following a daytime nap is contingent on strength of initial task acquisition.

Laboratory of Cognitive Neuroscience and Sleep, Department of Psychology, Program in Cognitive Neuroscience, The City College of the City University of New York, New York, NY, USA. mtucker1@bidmc.harvard.edu

STUDY OBJECTIVES: In this study we examined the benefit of a daytime nap containing only NREM sleep on the performance of three declarative memory tasks: unrelated paired associates, maze learning, and the Rey-Osterrieth complex figure. Additionally, we explored the impact of factors related to task acquisition on sleep-related memory processing. To this end, we examined whether testing of paired associates during training leads to sleep-related enhancement of memory compared to simply learning the word pairs without test. We also examined whether strength of task acquisition modulates sleep-related processing for each of the three tasks. SUBJECTS AND PROCEDURE: Subjects (11 male, 22 female) arrived at 11:30, were trained on each of the declarative memory tasks at 12:15, and at 13:00 either took a nap or remained awake in the sleep lab. After the nap period, all subjects remained in the lab until retest at 16:00. RESULTS: Compared to subjects who stayed awake during the training-retest interval, subjects who took a NREM nap demonstrated enhanced performance for word pairs that were tested during training, but not for untested word pairs. For each of the three declarative memory tasks, we observed a sleep-dependent performance benefit only for subjects that most strongly acquired the tasks during the training session. CONCLUSIONS: NREM sleep obtained during a daytime nap benefits declarative memory performance, with these benefits being intimately tied to how well subjects acquire the tasks and the way in which the information is acquired.

PMID: 18274266 [PubMed - indexed for MEDLINE]

PMCID: PMC2225575