Many adolescents experience partial sleep deprivation

Dr Kathryn Reid, Northwestern University

The results, presented at the American Academy of Neurology's annual meeting in Denver on Friday, show that young people sleep on average 8.5 hours on weekdays and more than 9.5 on weekends.

Sleeping longer

Dr Kathryn Reid studied the sleeping habits of 729 young people between the ages of 12 and 17 who were admitted to a local juvenile temporary detention centre.

In line with previous studies, she found that older teenagers were more likely to go to sleep late and wake up late.

But she also discovered that they slept longer than other researchers have suggested.

Half of the group also complained about being tired during the day - supporting previous conclusions that many teenagers may suffer from sleep deprivation.

Dr Reid said: "Previous research has indicated that sleep-wake habits of teenagers vary from those of adults and younger children, and that many adolescents experience partial sleep deprivation."

Cultural differences

But Prof Chris Idzikowski, of the British Sleep Society, said more research was needed.

He added that cultural differences between the US and other countries, including the UK - such as earlier school starts - meant the findings of studies carried out there did not always apply elsewhere.

He said: "There are major cultural differences between countries. It you compare Italy, Japan and the UK with the US, for example, it is striking how different school start times are and how education is organised."

But he added: "Certainly, it is something to stop and think about."