How Does Sleep Affect Success at School?

When a child has difficulty listening to detailed instructions or focusing on planned activities or is slow to react to a question, lack of sleep is often the culprit. It also inhibits time management and task prioritization, Dr. Judith Owens says. Because of this, the child might miss out on information learned at school.

If your preschooler has trouble describing a painting she made at school, she could benefit from more sleep. A 1998 study published in Sleep journal showed that just one night of insufficient sleep impaired verbal creativity and abstract thinking in children. "The ability to spontaneously come up with words was compromised," Dr. Judith Owens says.

A good night's sleep keeps your little one's brain fresh and helps him retain information. When paired with slow-wave sleep, rapid eye movement (REM) sleep—the stage where dreaming occurs—plays an essential role in memory consolidation, Dr. Judith Owens says. When your preschooler learns a new color or the words to a new song at school, REM sleep helps to solidify this information in her brain. "Almost everything preschoolers learn is new," she says.

When your little one feels fatigued during the day, he won't yawn or doze off like you do—he'll start bouncing off the wall. Why? Preschoolers "tend to get wired," Dr. Judith Owens says. "They get hyper and irritable." And if they can't sit still, they'll have a harder time learning.

Irritability, constant crying, temper tantrums, zero patience: Preschoolers who skimp on sleep are much less able to control their emotions. As a result, moodiness might affect their social standing with their peers. "If they're aggressive and oppositional with other kids, it impacts social interaction," Dr. Judith Owens says.

Sleep deprivation might weaken the immune system, making the body more susceptible to infection and disease. It also shifts the balance of hormones in the body—particularly essential growth hormones, Dr. Judith Owens says. And although it's not proven, this could cause your little one to get sick more frequently, resulting in missed school days.