Teenagers who stay up late into the night are three times more likely to suffer from asthma and hayfever, a study has shown.

Study author Dr Subhabrata Moitra, of the University of Alberta in Canada said, "Our results suggest there's a link between preferred sleep time and asthma and allergies in teenagers."

The research team surveyed 1,700 13 and 14 year olds, dividing them after a series of questions into evening types, morning types and inbetweeners. They found that those who preferred to sleep late were three times as likely to have asthma and twice as likely to have hayfever.

Prof. Thierry Troosters, president of the European Respiratory Society, said, " We need to know much more about why asthma and allergies are rising in children and teenagers and, hopefully, find ways to reduce these conditions. "This is the first study to examine the possible role of different sleep preferences in teenagers' risk of asthma and allergies, and it opens up an interesting and important new line of research."

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