Napping could be beneficial for children as old as 12, according to new research.

The link between sleep and behaviour will be nothing new to parents: the study includes anecdotal evidence that shows how mood, energy levels, and school performance are affected. But more surprising is the advanced age to which napping is shown to be of benefit, with the study focusing on children 10-12 years old.

“The more students sleep during the day, the greater the benefit of naps,” said Sara Mednick, an associate professor at the School of Social Sciences, University of California, who worked on the study with colleagues from the University of Pennsylvania.

“Many lab studies across all ages have demonstrated that naps can show the same magnitude of improvement as a full night of sleep,” she said. “Here, we had the chance to ask real-world, adolescent schoolchildren.”

Entrenching good sleep habits at an early age may be important for long-term health. Deprivation can cause clumsiness and accidents, for example falling asleep while driving. Sleep deficiency is linked to chronic health problems, including heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity and depression.

Sleep: how much is enough?
Image: American Academy of Sleep Medicine

The researchers collected data about napping frequency and duration from nearly 3,000 fourth, fifth, and sixth graders in China and assessed information on psychological measures, such as grit and happiness, as well as physical measures such as body mass index. They also collated behavioural and academic information about each student.

After adjusting for sex, grade, school location, parental education, and nightly time in bed, they showed strong connections between 30 to 60 minutes of daytime sleep at least three days a week and positive outcomes.

Napping was associated with higher levels of happiness, grit, and self-control, and better verbal IQs. The most robust findings were associated with academic achievement, according to Penn neurocriminologist Adrian Raine, a co-author of the paper. More work is needed to explore why children with better-educated parents nap more than children with less educated parents, or how nap interventions could be advanced on a global scale, they said.

The research shines a light on how sleep culture varies around the world, as it was conducted in China where napping continues past early childhood. In contrast, youngsters in the US and UK typically drop their naps before they’re 5 years old. Adult workers can break for sleep in China, Spain and other countries.

Other academic work underscores the benefits of rest for children. Sleep researchers at the University of Massachusetts Amherst linked naps and overnight sleep to both better memory in early childhood and emotion processing.

“A common observation of parents and preschool teachers is that children seem either grumpy or giddy when they skip their nap,” says the study’s lead neuroscientist Rebecca Spencer. “Our results are consistent with these observations of caregivers. Naps do contribute to emotion processing at this young age.”

In a separate paper, they showed that preschoolers who watch TV sleep significantly less than those who don’t.

While the health and lifestyle benefits of sleep have been well documented, sleep deficiency remains a common public health problem around the world.