For a small child, one of the biggest jobs he or she has is learning words. At least 10 hours of sleep over 24 hours will help, according to a study at the University of Arizona (UA). “Slow wave” deep sleep, in particular, helps us preserve memories.

The research team, led by doctoral student Michelle Sandoval, recruited 39 three-year-olds who seemed to be developing at the usual rate. Some of them napped four or more days a week; others less often. Around the age of three, many children are down to one nap or no naps a day.

Experimenters taught the children two made-up verbs—"blicking" and "rooping"—and showed them a video in which two different actors demonstrated an action corresponding to that verb. Verbs are usually more difficult to learn than nouns at that age.

In the next hour, half the children were asked to nap for at least a half hour, while the other half didn’t.

Twenty-four hours later, the children watched a video of two new actors performing the same actions they learned the previous day and were asked to point at which person was "blicking" and which was "rooping."

It turned out that children who had napped after the lesson were more likely to remember the meaning of “blicking” and “roping”—whether or not they were habitual nappers.

“The brain is replaying [memories] and strengthening them" during parts of the sleep cycle, said study co-author Rebecca Gómez, who is principal investigator of the UA's Child Cognition Lab. Sleep also calms us down. The stress hormone, cortisol, falls dramatically, and your child is likely to wake up happier and more alert and curious.

Don’t fret if your child won’t nap during the day, or immediately after a lesson, she said. A 10- to 12-hour night's sleep will also help your child learn. Aim for that total, whether it includes naps or not.

Set up a regular time and ritual for naps, Gomez suggests. One child may be very different from another in how she naps, but try to keep a schedule.

Two-year-olds are often ready to snooze after lunch. Try reading her a story and settling her in a quiet, dark room. If she says she’s not sleepy, suggest “quiet time,” and put on some gentle music.

Sometimes a vacation or other change in routine can push naptime later in the day and then move bedtime even later. Richard Ferber, MD, author of Solve Your Child's Sleep Problems, suggests maintaining the same number of hours between nap and bedtime. You can gradually move up naptime by 10 or 15 minutes, and another 10 or 15 minutes the next day. (Yes, this is the controversial Ferber, who has suggested that babies be left to soothe themselves to sleep. But you don’t have to adopt all his methods to try this one!)

To help a toddler sleep in day care, pick out a spot together and bring her a stuffed animal or other comforting object.

If an older sibling is keeping your little one up, enlist big brother or sister’s help in conducting any pre-nap rituals.

If your child gets out of bed, firmly and calmly walk her back. If that doesn’t work, be sure to make sure she’s getting enough sleep at night.

A version of this story appears at Your Care Everywhere. 

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