By Sarah D. Sparks

For schools looking for ways to squeeze in more instructional time for young learners, preschool and kindergarten nap time can be a tempting target.

But emerging sleep research suggests cutting out the afternoon snooze can come at the expense of some children’s longer-term ability to remember what they learn.

There’s no nationwide data on how many students nap in school. But in an ongoing series of experiments funded by the National Science Foundation, cognitive researchers Rebecca Spencer of the University of Massachusetts Amherst and Tracy Riggins of the University of Maryland are tracking how young children make the transition from …