Insomnia is the curse of Generation X-Box

The problem is especially pronounced among young boys, with thousands now being treated every year.

Experts say parents are at fault for failing to enforce strict bedtimes and allowing children to play computer games and watch TV in their rooms late at night.

Eating too much sugary food is also blamed for preventing children from dropping off to sleep.

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Newly released NHS figures show that the number of under-11s referred to hospital specialists for insomnia, sleep-walking and sleep-related breathing problems has rocketed by 26 per cent over the past five years.

But the true numbers affected could be much higher because the figures reflect only those seeking medical help.

Studies have linked poor sleep to Attention Deficit Hyperactivity Disorder (ADHD). And lack of sleep harms children's ability to learn at school.

Psychologist Chireal Shallow, of the Naturally Nurturing clinic for children's sleep disorders in London, said: "There are likely to be thousands more children whose parents do not seek treatment.

!"A lot of the problem is guilty parenting where kids are allowed the rule of the roost because Mum and Dad come home from work late.

"Increasingly, we also don't let children play outside because of modern dangers and instead put them in front of a screen to keep an eye on them.

"The light, sound and movement of television or computer screens is stimulating and keeps children awake and there should be at least an hour's gap before going to bed."

Nick Seaton, chairman of the Campaign for Real Education, said: "It's absolutely crazy for parents to let their children go to bed any time they like.

"It's obviously going to create problems for youngsters later in life and is part of the general problem of poor discipline in homes and schools.

"Parents need to exert more authority and remove computer games from bedrooms to make sure kids have the best start in life. I'm sure teachers would be delighted."

The NHS statistics show nearly 3,000 children under 11 had their sleep monitored overnight by specialists during 2006 compared with only 2,200 in 2002.

Of those, 1,733 were boys.

Professor Jim Horne of the Sleep Research Centre at Loughborough University, said that children aged five to eight are particularly vulnerable to sleep problems as a result of 'electronic distractions' because having a rigid bedtime routine is so important to them.

He said computers and mobile phones in bedrooms could be contributing to the growing number of sleep problems.

Prof Horne added: "Staying up late should be a special treat. Children who persistently go to bed late get into hyperactive states and learning becomes a problem at school the next day.

"You could speculate that some behavioural issues in schools are caused by sleeping problems.

"There is increasing evidence that about one in five children diagnosed with ADHD actually have sleep problems that cause hyperactivity.

"If they sleep better, the ADHD symptoms disappear."

Jane Howell, 34, from Morden, South West London, struggled for years to get her son Marcel, now 13, to sleep.

After spending most of the day at school in front of a computer, Marcel would spend the evenings watching television but then found it hard to drop off, often not falling asleep until just a few hours before he had to be up again. "Eventually the problem got so bad that Jane approached a sleep clinic. "She said: "The clinic asked me about his routines and said computers, televisions and mobile phones were a distraction.

"They told me to minimise the time he uses computers and after 8pm it's now wind-down time.

"He now has much more energy and is sleeping better. As parents you have to be hard on your kids. They want to do their own thing but you have to be strict."

Dr Rob Primhak, a consultant paediatric respiratory physician at Sheffield Children's Hospital, said there was now a shortage of specialists due to the numbers coming in.

"There has been a huge surge in demand," he said.

Mandy Gurney, of the Millpond Children's Sleep Clinic in London, said: "Not getting a good night's sleep can have the same effect as four units of alcohol, so imagine what it is like for a child."