Daytime naps, motor memory consolidation and regionally specific sleep spindles.
Level 2 - randomized trial
Controlled experimental laboratory trial with intervention (nap) and control (wake) groups (design analogy).
PubMed 17406665 · doi:10.1371/journal.pone.0000341
What was done
Two groups of participants trained on a left-hand motor-skill task in the morning and underwent re-testing 8 hours later. One group took a 60–90 minute intervening midday nap, while the other group remained awake. Researchers evaluated offline memory consolidation alongside electrophysiological sleep metrics, including global stage-2 NREM sleep and topographical sleep spindle activity across the learning (right) and non-learning (left) motor hemispheres.
What was found
The abstract reports no raw numerical scores, group sizes, or exact p-values. Participants who remained awake exhibited no significant performance improvement upon re-testing, whereas the nap group demonstrated a significant consolidation enhancement. Within the nap group, performance improvement correlated positively with global stage-2 NREM sleep. In addition, subtracting spindle activity of the non-learning hemisphere from the learning hemisphere revealed a strong positive relationship with memory consolidation that was not present when analyzing either hemisphere alone.
Why it matters
The study suggests daytime naps actively support motor memory consolidation, linking behavioral improvements to localized, hemisphere-specific sleep spindle activity rather than solely global sleep stages.
Limits
The abstract omits sample size, participant characteristics, randomization details, and exact statistical estimates (such as effect sizes or correlation coefficients). Testing was restricted to a single motor task over an 8-hour period, so long-term durability and generalizability to other motor or cognitive skills remain unmeasured.
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