Caregivers know a napping child usually means a less cranky child later in the day, but a new study shows another benefit to a midday rest, improved learning skills. A new study shows napping can help improve learning. Researchers tested the memory of 40 preschoolers, once after the children napped and once after they skipped the midday rest. The study found children who stayed awake forgot 15% of the information they learned in the morning, whereas when the children took naps they remembered everything they had learned. Researchers measured little bursts of activity in the brain called sleep spindles during the children's naps, which represents markers of plasticity of when the brain is really susceptible to forming new memories. Experts say about an hour of napping is all it takes.