http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/04/01/nsleep201.xml

Surly teenager syndrome could be cured by an extra hour in bed, research shows.

A study found that secondary school children are biologically programmed to need more sleep and at different times than adults.

It concluded that, rather than despairing at behaviour like that of Harry Enfield’s Kevin the Teenager, parents should feel sympathy because it is probably the result of a considerable “sleep debt”.