The "terrible twos" and "trying threes" might just boil down to a lack of naps.
Toddlers between 2 1/2 and 3 years old show more anxiety, less joy and interest, and have a harder time solving problems when they miss a nap. What's more, says research from the University of Colorado in Boulder, over the long haul, chronically missing naps may make children more prone to temper tantrums—and set them up for a lifetime of mood disorders and other mental health issues.
All this from missing one little one-hour nap?
In the study, researchers measured the sleep patterns of toddlers by having children wear a special device which measured how much they slept. Study author Professor Monique LeBourgeois then filmed the toddlers' facial expressions as they completed two jigsaw puzzles on one day where they'd had their usual nap, and on another when they had skipped it, according to a University press release.
Results showed that tired tots who successfully completed the first puzzle were much less positive in their response to this accomplishment than they had been when well rested. When kids were given another deliberately unsolveable puzzle (one puzzle piece was changed), researchers note that tired toddlers were noticeably more stressed by it than when they'd enjoyed their usual nap. Toddlers who had missed out on a nap were also much less curious about the unsolveable puzzle.
"This study shows insufficient sleep in the form of missing a nap taxes the way toddlers express different feelings, and, over time, may shape their developing emotional brains and put them at risk for lifelong, mood-related problems," says LeBourgeois.
Parents probably don't need a study to tell them that lack of napping often leads to cranky toddlers. But if you need help getting your tot to slow down long enough during the day to take a nap, try taking a cue from what works at bedtime—set up an afternoon routine that includes snuggling, stories, and keeping your child's room quiet and dim.
"Many young children today are not getting enough sleep, and for toddlers, daytime naps are one way of making sure their 'sleep tanks' are set to full each day," says LeBourgeios.