If there’s one thing that we love to stress about, it’s technology and kids. Nothing inspires more gratuitous fear than the idea that we might be harming our children by letting them near an iPhone. Screens have become the ultimate boogeyman, being blamed for everything from mental health problems to cancer. Partly that’s because we love to hate things we don’t understand, but it’s also because of our pervasive belief that anything new must, by definition, be a danger to our very souls.
So it’s no surprise that when a study suggested that late nights in front of screens might be giving teenagers asthma, the media jumped on the story in a second. Headlines everywhere have been proclaiming that teens who stay up late (probably in front of screens) are giving themselves asthma and respiratory problems with their nocturnal habits.
Fortunately, while it sounds scary, the evidence doesn’t really support that at all.
Late nights probably aren’t giving teens asthma.
The study that has the news media agog was a simple epidemiological paper looking at night-time habits of teenagers in West Bengal. The authors asked teens about their “chronotype” — essentially whether they were morning, afternoon, or nighttime people — as well as whether they had asthma symptoms. After correcting for potential confounders — things that can cause both the exposure (chronotype) and outcome (asthma) of interest, and thus muddy the results — they found that teens who stayed up late at night were more likely to report having asthma than teens who didn’t.
Cue the scary headlines warning teens to go to bed early.
Except, it’s not quite as simple as that. Even the study itself didn’t claim that this was a causal relationship — there’s no real way of knowing whether late nights were actually making kids have asthma. All the researchers did was a cross-sectional survey asking about sleep habits and asthma symptoms. With most blogs, I’d go through a lengthy diatribe listing the flaws in the research that make the news headlines mostly meaningless, but there are so many there’s not much point. So instead, here’s a short list of some of the iggest issues that make this study worthless in terms of determining whether late nights actually cause asthma:
- Reverse Causality — there’s evidence that asthma changes sleeping behaviours. With a single survey, we have no idea whether kids with asthma prefer to stay up late, or if the asthma is caused by the lack of sleep.
- Residual Confounding — the authors controlled for some confounders, but with a survey like this there are always more. Income, education, race, and numerous other things that the study didn’t account for could’ve influenced the results.
- Recall Bias — When you ask people to answer a survey about their lives, they are prone to recalling things incorrectly. Maybe people who stay up late are just better at remembering their asthma symptoms? We have no way of knowing.
- Generalizability — Given that this was a survey of adolescents in West Bengal, it’s hard to know if the results apply to kids in the rest of the world.
- Sample Size — While the survey itself was large, there were very few kids who were the night owls the study was worried about. In fact, given the low number of late night lovers, the statistical model used in the study may not have been ideal.
Realistically, while this study may have found an interesting association, it really isn’t any more than that. The only thing you can take home from this piece of research is that West Bengalese teens who report staying up late also report asthma a bit more often than those who have earlier bed times.
Sadly, that doesn’t make as good a headline as “Staying up late may be killing your kids, study says”.
We’re not going to stop being scared of screens. They are the technological feat that we love to hate, and even those of us who use them all the time sometimes wish that we could go back to a time without Twitter.
That being said, the evidence is much less worrying than many media stories make it seem. Time and again scientists have found associations between more screen use and health, but it’s almost never as solid a link as the headlines would lead you to believe. It’s also not surprising that more or less screen time has a vague link to health, because the distribution of screen use in society is not even — families who have no money for fancy things like music and arts lessons almost certainly use screens more than the wealthier crowd. It’s hardly unexpected that teens who use screens more might be a bit less healthy than those who use them less, because they are different in any number of other ways as well.
Ultimately, this study didn’t show that screens are bad for children’s health, but that’s a fairly common theme with this sort of research. It is fiendishly difficult to disentangle the cause and effect here, because lots of things impact your likelihood of being sick and using a screen.
Next time you read a headline saying that screens are destroying your children’s lives, take a second to think about what the research actually says. It might be that this is just a vague correlation that has little meaning on your life after all.