A daytime nap combined with nighttime sleep promotes learning in toddlers.

Napping after learning promotes consolidation of new information during infancy. Yet, whether naps play a similar role during toddlerhood, a stage when many children are beginning to transition away from napping, is less clear. In Experiment 1, we examined whether napping after learning promotes generalization of novel category exemplars 24 h later. Young children (N = 54, age range = 29-36 months) viewed three category exemplars in different contexts from each of three categories and remained awake (No-Nap condition) or napped (Nap condition) after encoding and were then tested 24 h later. Children who napped after learning showed superior generalization 24 h later relative to children who did not nap. In a Nap-Control condition tested 4 h after awakening from a nap, children performed at the same low level as in the No-Nap condition, indicating that generalization stemmed from an additional period of nighttime sleep and not simply from a nap or increased time. In Experiment 2, we examined whether nighttime sleep is sufficient for generalization if it occurs soon after learning. An additional group of children (N = 18) learned before bedtime and were tested 4 h after waking up the next day. Children did not generalize as well as those who had a nap combined with subsequent nighttime sleep. These findings suggest that naps, when combined with a period of nighttime sleep, might help toddlers to retain newly learned information and lead to delayed benefits in generalization.