The growing number of gadgets owned by teenagers is having a negative impact on their sleep patterns, according to new research.

The increasing popularity of mobile phones, music systems and televisions in teenagers' rooms is causing "junk sleep", according to the Sleep Council, an organisation funded by the National Bed Federation that represents British bed manufacturers.

In a poll of 1,000 children aged between 12 and 16, almost all admitted to having a phone, music system or TV in their bedroom. Just under two thirds had all three items. Nearly three in five (58 per cent) of the 12- to 14-year-old boys questioned said they had a phone, music player, TV and games console in their bedroom.

As a result of these distractions, nearly one in three of all those questioned got just four to seven hours of sleep each night. The Sleep Council recommends eight to nine hours' sleep each night for children in this age group. Almost a quarter admitted to falling asleep while watching TV or using other gadgets more than once a week.

Just one in ten children questioned said that they gave much thought to the quality of sleep they get. When asked how they thought sleep affected them they ranked energy levels as being the most affected followed by mood, school work, hair and skin, and weight.

Dr Chris Idzikowski, a sleep expert at the Edinburgh Sleep Centre, said: "This is an incredibly worrying trend. What we are seeing is the emergence of Junk Sleep that is of neither the length nor quality that it should be in order to feed the brain with the rest it needs to perform properly at school.

"Youngsters need to be taught a healthy lifestyle includes healthy sleep as well as healthy food. The message is simple: switch off the gadgets and get more sleep."