Students are often stereotyped as the laziest members of society, but new research has questioned the validity of this assumption.

Professor Russell Foster, chairman of circadian neuroscience at Brasenose College, Oxford, has conducted a series of tests and concluded that people aged 10 to 20 need about nine hours of sleep a night for full cognitive performance.

He believes students perform better in the afternoon because their body clock is programmed about two hours later, possibly for hormonal reasons.

Professor Foster said of the research: “There’s a biological predisposition for going to bed late and getting up late. Clearly you can impose upon that even worse habits, but they are not lazy.”

He has stressed students should not over-indulge in sleep, but makes the suggestion that starting University days one hour later and placing more demanding subjects later in the day would reduce incidents of absenteeism and depression.