Toronto, Jul 6 (IANS): Dear parents, if your teenage child is not going to bed early and is hooked to screen late in night, read this carefully.

Researchers, including one of Indian-origin, have found that teenagers who prefer to stay up late and wake later in the morning are more likely to suffer from asthma and allergies compared to those who sleep early.

Asthma symptoms are known to be strongly linked to the body's internal clock, but this study, published in ERJ Open Research, looked at how individual sleep preferences influence asthma risk in teenagers.

According to the researchers, the study reinforces the importance of sleep timing for teenagers and opens up a new channel of research into how sleep affects teenagers' respiratory health.

"Sleep and the 'sleep hormone' melatonin are known to influence asthma, so we wanted to see if adolescents' preference for staying up late or going to bed early could be involved in their asthma risk," said Subhabrata Moitra from the University of Alberta in Canada.

The study involved 1,684 adolescents living in West Bengal, India, aged 13 or 14 years, who were taking part in the Prevalence and Risk Factors of Asthma and Allergy-Related Diseases among Adolescents (PERFORMANCE) study.

Each participant was asked about any wheezing, asthma, or symptoms of allergic rhinitis, such as a runny nose and sneezing.

They were asked a series of questions to judge whether they were 'evening types', 'morning types' or in between, such as what time of the evening or night they tend to feel tired, when they would choose to wake up, and how tired they feel first thing in the morning.

Researchers compared the teenagers' symptoms with their sleep preferences, taking into account other factors that are known to affects asthma and allergies, such as where the participants live and whether their family members smoke.

They found that the chance of having asthma was around three times higher in teens who prefer to sleep later compared to those who preferred to sleep earlier.

They also found the risk of suffering allergic rhinitis was twice as high in late-sleepers compared to early-sleepers.

"Our results suggest there's a link between preferred sleep time, and asthma and allergies in teenagers," Moitra said.

"We can't be certain that staying up late is causing asthma, but we know that the sleep hormone melatonin is often out of sync in late-sleepers and that could, in turn, be influencing teenagers' allergic response," Moitra informed.