Paul Kelley, the headteacher of Monkseaton High School in Tyne and Wear, wants to re-shape the school day. His ambition is to start the school day a couple of hours later - 10am or after - so that teenagers will have had enough sleep to enable them to learn.

Another school, Hugh Christie Technology College in Kent, has already introduced major changes to its timetable. Older pupils start at 11.30am three days a week, have one day with no timetabled lessons and start at 8.30am on Fridays to allow them to have an early finish for the weekend.

Dr Kelley believes there is growing evidence that teenagers’ body clocks shift forward a couple of hours - and that schools need to respond to this by rearranging their timetable. He has been running a research project into teenagers’ body rhythms with Russell Foster, an Oxford academic and chairman of Circadian Neuroscience at Brasenose College, and has asked permission from his governors to introduce an 11am start from September.

But could allowing pupils to sleep in really have an impact on how they behave and perform at school? Research seems to support Dr Kelley’s argument, particularly when it comes to younger pupils. A recent study by Dr Michael Carr-Gregg, a leading Australian psychologist, found that 40 per cent of children with mobile phones are sleep deprived on school nights as they stay up until the early hours texting friends.

And in April this year, a Finnish study found a link between children who do not get enough sleep and symptoms of attention deficit hyperactivity disorder (ADHD). Researchers from the University of Helsinki found that those children who had less than 7.7 hours’ sleep each night were much more likely to show the troubled behavioural symptoms of ADHD.

“Sleep is being undervalued. We don’t seem to realise how important sleep is to young people’s wellbeing,” says Dr Juulia Paavonen, who led the research.

Her study has raised the question of whether the increase in the number of pupils with such attention-deficit problems - and wider concerns about behaviour - may at least in part be driven by a culture of sleeplessness. And if that proved to be the case, rather than reaching for medication it may be more effective to organise an earlier bedtime.

“Children who are not getting enough sleep are not showing signs of tiredness, but displaying signs of hyperactivity,” says Doctor Paavonen. While adults may be able to cope with reduced sleep, the emotional impact is more profound on children, she believes.

Western industrialised countries seem to have developed a blind spot to the physical significance of getting enough sleep. Concerns in many countries about children’s behaviour fail to take sleep into account, and this is a glaring omission, adds Doctor Paavonen.

Neil Stanley, a sleep researcher based at the University of East Anglia, believes the increase in distractions available to young people is to blame. “Children once had a bedtime routine - they didn’t stay up much after 9pm,” he says.

“There was no all-night television and not many other distractions - you could read a book under the bedcovers, but that was it.”

In sharp contrast, modern children are surrounded by temptations to stop them sleeping - the internet, television, DVDs, computer games, mobile phones and iPods. It becomes harder for them to switch off, with their bedtimes being pushed back further into the night. Even when they do unplug the electrical gadgets, youngsters need time to unwind before they can slip into sleep, says Dr Stanley.

A survey published last year warned of teenagers suffering from poor- quality “junk sleep” when it found that a quarter regularly fell asleep with gadgets such as televisions and iPods still playing.

Although children’s entertainment culture may have changed, their biological need for sleep has not, leaving them exhausted in the morning. “We’ve forgotten that children and teenagers need a lot of sleep,” says Dr Stanley.

He contrasts the massive political and financial investment in encouraging children to eat healthier food and to take more exercise with the apparent lack of action on sleep.

When there appears to be a link between lack of sleep and an excess of bad behaviour, he says it is remarkable that so little effort is made to improve sleeping habits.

“We don’t have the discipline with children to put them to bed,” he says. Instead of recognising the importance of sleep on children’s emotions and wellbeing we give them “mind-frying drugs”, he says.

What exasperates him is the way both adults and young people have come to accept sleep deprivation as normal - even though there is so much evidence that it causes physical and mental health problems. “We live in a tired society,” he says. “It’s socially acceptable to be knackered all the time.”

Sleep is important for learning, memory and growing, while lack of sleep is associated with problems such as obesity, bad behaviour and academic underachievement, adds Dr Stanley. But despite such a balance sheet, he believes that sleep remains under-appreciated.

“We’ve fallen out of love with sleep,” he says. “For most of human history we’ve recognised its importance, but that seems to have been lost.”

Part of the problem is that there is no industry to promote the cause of sleep. Healthy eating and exercise have major commercial backers, whether it’s supermarkets or designer trainers. But sleep isn’t a “product” that can be marketed, he says.

“You go into a newsagent’s and there are 50 different magazines on cookery or exercise,” he adds. “Who is there making an argument for sleep?”

Certainly, there has been plenty of evidence of the importance of sleep for learning. Neuroscientists at the University of Geneva have shown how a sound night’s sleep improves the performance of the brain in processing new experiences and consolidating information and ideas gathered during the day.

Tests have shown that insufficient sleep impairs problem-solving skills and the ability to carry out tasks. Studies reveal that getting only five hours’ sleep a night has the same effect on reaction times as being over the drink-driving limit.

And for anyone revising for exams, “sleeping on it” is good advice because sleep is strongly linked to improved memory.

A striking piece of research published last year showed that even the briefest period of sleep - just six minutes - can improve the ability of students to recall information. The study, conducted at the University of Dusseldorf, carried out memory tests which found that those students allowed to sleep after trying to memorise information, even for a brief catnap, had better results.

But what can schools do if they are faced in the morning with ranks of sleep-starved pupils? Despite his own belief that helping teenagers to get more sleep will improve their health and learning, Dr Kelley at Monkseaton has encountered “incredible cultural resistance to change”.

Although there is a physical need for sleep, there is still an attitude that sees more sleep as something associated with laziness rather than endeavour. Calling for more sleep seems to go against the grain.

Dr Kelley’s work with Professor Foster has looked at how lack of sleep affects performance. As well as reduced cognitive skills, Professor Foster reported an increased risk of mood swings, weight gain, poor communication and a lack of creativity.

The failure to take the issue of sleep seriously enough is “not malicious”, says Dr Kelley, but reflects a lack of knowledge about sleep and the health implications.

“The ability to do well in school, in learning and in general wellbeing is a function of health - and sleep is a big health issue,” he explains.

Dr Kelley says schools should think about pupils’ behaviour in the context of needing more sleep - such as greater irritability or loss of sense of humour. And there are other wider concerns that have been linked to sleep deprivation, he says, such as depression and problems with the immune system.

Dr Stanley agrees that we’ve reached a contradictory stumbling block in trying to tackle a “crisis in sleep”. Many people, children and adults, suffer the miserable consequences of not sleeping enough, but there is little social pressure to resolve it, he says.

“If you tell people you eat five pieces of fruit and vegetables a day and you do exercise, people think you’re very healthy. If you say you went to bed for 10 hours, they think there must be something wrong with you.”

If more schools follow the example of Hugh Christie and Monkseaton, assumptions like these could become a thing of the past

Sean Coughlan is the author of `The Sleepyhead’s Bedside Companion’, published by Preface, pound;12.99

HOW MUCH SLEEP DO CHILDREN NEED?

Age 5: 11 hours

Age 10: 9.75 hours

Age 15: 8.75 hours

Source: NHS.