Teenagers hooked on TV and computer games only get four hours' 'junk sleep' a night

One in three secondary school pupils survives on short bursts of "junk sleep" and turns up exhausted for lessons the next day, according to a survey.

The Sleep Council warned that its results showed parents were being too lenient compared to previous generations by failing to impose a strict "lights out".

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The report said sleep was a major problem for teenagers as many fail to get the eight or nine hours of highquality rest recommended.

Most blame computers or television for keeping them up but a significant number also lie awake worrying about relationships and exams.

Experts have linked poor-quality sleep with weight gain and under performance at school.

There is also evidence that a lack of sleep can increase cravings for sugary and high-fat foods.

Ninety-nine per cent of teenagers surveyed said they had a TV, music system or phone in their bedroom while two-thirds claimed to have all three.

More than half of boys aged 12 to 14 also had a games console in their room.

A fifth of boys in this age group admitted their quality of sleep was affected by leaving the TV or computer switched on.

Parents were also warned that having friends to stay for "sleepovers" on school nights increased the risk of children missing out on proper rest.

The Sleep Council, which promotes the importance of a good night's rest to health, also found that 30 per cent of teenagers were getting only four to seven hours sleep on a school night.

Almost a quarter said they fell asleep more than once a week while watching the TV, listening to music or with other electrical items running.

But only one in ten said they gave much thought to the quality of their sleep, despite 40 per cent admitting they generally felt tired in the day.

This rose to 50 per cent among girls aged 15 and 16.

At weekends, 9 per cent of boys aged 15 and 16 said they had less than four hours sleep.

More than half said they often lie awake worrying about problems such as exams or relationships.

Dr Chris Idzikowski, from the Edinburgh Sleep Centre, said: "I'm staggered that so few teenagers make the link between getting enough good sleep and how they feel in the day.

"Teenagers need to wake up to the fact that to feel well, perform well and look well, they need to do something.

"This is an incredibly worrying trend. What we are seeing is the emergence of 'junk sleep' - sleep that is of neither the length nor quality to feed the brain with the rest it needs to perform properly at school."

Dr Idzikowski also blamed parents for being too lenient and allowing teenagers to stay at each other's homes on school nights.

"For sleepover, it would be more accurate to say 'wakeover'," he said.

"Parents these days aren't necessarily as strict as they once were with the lights-out policy.

"And with so many distractions, the amount of sleep achieved when at friends has to be highly questionable."

Almost a quarter of teenage girls said they slept over with friends once a week or more and a fifth of boys said the same.