AMERICAN children are more sleep-deprived than ever, with more than a quarter reporting that they doze off in class at least once a week, a study published yesterday says.

Many arrive at school late because of oversleeping and others are driving to classes drowsy, according to a survey released by the National Sleep Foundation.

“In the competition between the natural tendency to stay up late and early school start times, a teen’s sleep is what loses out,” Jodi Mindell, the associate director of the Sleep Centre at the Children’s Hospital of Philadelphia, said.

The survey found that 11-year-olds were sleeping an average of 8.4 hours a week on school nights, 17-year-olds only 6.9 hours. School-age children and teenagers should get at least nine hours’ sleep a day, the National Centre on Sleep Disorders Research at the National Institutes of Health says. It adds that there is growing evidence linking a chronic lack of sleep with an increased risk of obesity, diabetes, heart disease and infections.

The researchers report that 28 per cent of high-school students said they fell asleep in class at least once a week. Twenty-two per cent dozed off while doing homework and fourteen per cent arrived late or missed school because of oversleeping.

Nearly all schoolchildren — 97 per cent — have at least one electronic item in their bedroom, such as a television set, a computer, a phone or a music device. Nearly 30 per cent said that they were too tired to exercise.

Four fifths of students who get the recommended amount of sleep are achieving grades of A and B in school. Those who get less sleep are more likely to achieve lower grades. “Sending students to school without enough sleep is like sending them to school without breakfast,” Ms Mindell said. “Sleep serves not only a restorative function for adolescents’ bodies and brains, but it is also a key time when they process what they’ve learnt during the day.”

Researchers in the UK believe that modern lifestyles are to blame for almost two thirds of British children not getting enough sleep. They say that by the time they are 7, some children will have missed 4,500 hours of sleep.

Professor Jim Horne, of Loughborough Sleep Research Centre, says that such children will become hyperactive and irritable. He blames a change in emphasis that means bedrooms, far from being places of peace and rest, are now full of computers and televisions.

Ms Mindell says: “Those with four or more electronic devices in their bedroom were twice as likely to fall asleep in school.” Many teenagers keep mobile phones on at night. The researchers said that, as children reached puberty, their body clocks tended to readjust to two hours later, so they were more alert at night and sleepier in the morning.

Only 20 per cent of adolescents said that they got nine hours of sleep on school nights and 45 per cent reported sleeping less than eight hours. “We call on parents, educators and teenagers themselves to take an active role in making sleep a priority,” Richard Gelula, the foundation’s chief executive officer, said.

According to experts, sleep needs vary from person to person and change throughout life. Newborns sleep 16 hours to 18 hours a day; children in pre-school sleep 10 hours to 12 hours; school-age children and teenagers should get at least 9 hours. Adults should get up to eight hours.

LAND OF NOD

The longest period without sleep is believed to be 11 days, set by Randy Gardner, an American, in 1964

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