How learning happens in the brains of sleeping babies

In the United States, politicians and school superintendents have often argued that preschools should focus on instruction, not sleeping. And in some parts of the country, educational standards have shifted to reflect that idea. For instance, in Massachusetts where Spencer works, teachers tell her the amount of preschool time set aside for napping has decreased in the last 10 to 15 years. Standards also have loosened around making classrooms conducive to sleep, for instance by enabling teachers to darken rooms during naptime. In some schools, parents can choose to send younger kids to swim lessons or Zumba fitness classes instead of napping, Spencer says. She’s worried about the effect that has on learning.