Practice and nap schedules modulate children's motor learning

Night- or day-time sleep enhances motor skill acquisition. However, prominent issues remained about the circadian (time-of-day) and homeostatic (time since last sleep) effects of sleep on developmental motor learning. Therefore, we examined the effects of nap schedules and nap-test-intervals (NTIs) on the learning of finger tapping sequences on computer keyboards. Children aged 6-7, 8-9, and 10-11 years explicitly acquired the short and long tapping orders that share the same movement strings (4-2-3-1-4, 4-2-3-1-4-2-3-1-4). Following a constant 8- or 10-hr post-learning period in one of the four NTIs (2, 4, 5, 7 hr), children in the morning napping groups, the afternoon napping groups, or the waking group performed the original long sequence in retention test (4-2-3-1-4-2-3-1-4) and the mirrored-order sequence in transfer test (1-3-2-4-1-3-2-4-1). Age and treatment differences in the movement time (MT, ms) and sequence accuracy (SA, %) were compared during skill learning and in retrieval tests. Results suggest that practice or nap affects MT and SA in a greater extent for the younger learners than for the older learners. The circadian effects might not change nap-based skill learning. Importantly, the longer NTIs resulted in superior retention performance than the shorter ones, suggesting that children require a relatively longer post-nap period to form motor memory. Finally, nap-based motor learning was more marked in skill retention than in skill transfer. Brain development may play an important role in motor learning. Our discussion centers on memory consolidation and its relevance for skill acquisition from early to late childhood.