Teenagers who go to bed late ‘more at risk of asthma’

ConvinCing your teenage child to go to sleep at a sensible hour can be a thankless task.

But it might be worth persisting with the nagging, as scientists have found that a stricter bedtime could reduce the risk of youngsters getting asthma.

Those who went to bed late and got up late were almost three times more likely to have asthma, or to have suffered from it previously, according to a study.

People with asthma have ‘sensitive’ airways, and their immune system is believed to overreact to triggers like dust, pollution and exercise. Their airway swells and narrows, leaving them gasping for breath.

This may be more likely in latesleeping teenagers because they disrupt their body clock, which some experts believe has a knockon effect on the immune function of their lungs.

Teenagers who spend long evening hours hunched over smartphones and tablets may make this worse, as the blue light from the devices further changes their body’s ability to distinguish night from day.

Researchers studied almost 1,700 teenagers, with nearly one in ten being self- confessed ‘night owls’. That was compared to ‘larks’ who got up and went to bed early. These night owls were almost three times more likely to suffer allergic symptoms with a similar cause to asthma, such as sneezing and a runny nose.

Dr Subhabrata Moitra, senior author of the study from the University of Alberta in Canada, said: ‘Teenagers are not naturally night owls, whatever they might think. But our results suggest there’s a link between the time they prefer to go to sleep, and asthma and allergies.

‘So the advice to parents, based on these findings, might be for them to make sure their young teenagers go to bed between 9.30 and 10.30pm, and put down their electronic devices two hours before that.’

The study recruited teenagers aged 13 and 14, asking them what time in the evening they tended to feel tired, ranging from before 9pm to after 2am.

other questions included what time of day they felt best and how tired they were in the morning.

it emerged 9 per cent of the teenagers identified as night owls, 42 per cent were larks and the rest fell somewhere in between, according to the study, published in the journal ERJ open Research.