An afternoon nap can boost happiness as well as improve behaviour and academic performance of children, a study has found.
Researchers from the University of California (UC) Irvine in the US conducted a study of nearly 3,000 fourth, fifth, and sixth graders aged 10-12.
The study, published in the journal SLEEP, showed a connection between midday napping and greater happiness, self-control, and grit; fewer behavioural problems; and higher IQ.
"Children who napped three or more times per week benefit from a 7.6 per cent increase in academic performance in Grade 6," said Adrian Raine, from University of Pennsylvania.
"How many kids at school would not want their scores to go up by 7.6 points out of 100?" Raine said.
Sleep deficiency and daytime drowsiness are surprisingly widespread, with drowsiness affecting up to 20 per cent of all children, said Jianghong Liu, an associate professor at the University of Pennsylvania.
While the negative cognitive, emotional, and physical effects of poor sleep habits are well-established, and most previous research has focused on preschool age and younger.
Researchers used data from a study in China, where the practice of afternoon napping is embedded in daily life, continuing through elementary and middle school, even into adulthood.
From each of 2,928 children, the researchers collected data about napping frequency and duration once the children hit Grades 4 through 6, as well as outcome data when they reached Grade 6, including psychological measures like grit and happiness and physical measures such as body mass index and glucose levels.
They also asked teachers to provide behavioural and academic information about each student.
The researchers then analysed associations between each outcome and napping, adjusting for sex, grade, school location, parental education, and nightly time in bed.
"Many lab studies across all ages have demonstrated that naps can show the same magnitude of improvement as a full night of sleep on discrete cognitive tasks," said Sara Mednick, from UC Irvine.
"Here, we had the chance to ask real-world, adolescent schoolchildren questions across a wide range of behavioural, academic, social, and physiological measures," said Mednick.
"The more students sleep during the day, the greater the benefit of naps on many of these measures," she said.
Though the findings are correlational, the researchers say they may offer an alternative to the outcry from paediatricians and public health officials for later school start times.