Are you smarter than a fifth grader? Scratch that. Are you as smart as a preschooler?

What’s the one thing most preschoolers do that may give them an intellectual boost? They take long afternoon naps.

Preliminary research from a team at the University of California at Berkeley suggests that long afternoon naps prime the human brain to remember things. The researchers conducted an experiment using 39 subjects. At noon, the subjects participated in a memory test in which they were required to recall faces and link them with names. The group was then divided, with half of the members napping for 100 minutes and half remaining awake. When they retook the test at 6 p.m., those who skipped the nap performed about 10 percent worse than those who enjoyed a little sleepy time. And, though people have been shown to demonstrate a natural learning decline between the hours of noon and 6 p.m., the nappers were able to offset that decline.

The key to naptime success, says study author Matthew Walker, is sleeping long enough for the brain to go through various sleep cycles. With the help of electroencephalograms to track the brain’s electrical activity, the researchers determined that the memory-boosting functions seemed to take place between the deep-sleep and the dream (or rapid eye movement) states.

Although more research is necessary, the study suggests that an afternoon nap of, say, 90 minutes or more could be helpful to students or older people struggling with memory issues.