Children who get less than nine to 11 hours a day of sleep, a new study says, and who use screens more than two hours each day are more likely to behave impulsively.

The study looked at the data collected from 4,524 children to compare sleep hours, screen hours and physical activity against eight measures of impulsivity including “one’s tendency to seek out thrilling experiences, to set desired goals, to respond sensitively to rewarding or unpleasant stimuli, and to act rashly in negative and positive moods.” The study, 24-Hour Movement Behaviours and Impulsivity, was published in the journal ‘Pediatrics’ and looked at children between the ages of eight and eleven.

Children who get less than nine to 11 hours a day of sleep, a new study says, and who use screens more than two hours each day are more likely to behave impulsively. Researcher Michelle Guerrero explains how too little sleep and too much screen time can affect a child’s behaviour. 7:57

Michelle Guerrero is lead author, and a postdoctoral fellow at the CHEO Research Institute in Ottawa. She spoke with the CBC’s Conrad Collaco about how too little sleep and too much screen time can affect a child’s behaviour. You can read an abridged and edited version of the interview or listen to the full audio interview by hitting the play button above.

Michelle Guerrero, CHEO Research Institute in Ottawa

You were looking at the connection between impulsive behaviour and what’s known as 24-hour movement behaviour. What does that mean?

So, the Canadian 24-hour movement behaviour guidelines recommend that children and youth between the ages of five to 13 accumulate a minimum of 60 minutes of moderate to vigorous physical activity and no more than two hours of recreational screen time per day and nine to eleven hours of uninterrupted sleep per night.

What did you see when kids get the recommended amount of sleep and screen time?

We found that when children met the three movement behaviours — so when they were active and they reduce screen time and they accumulated a good night’s sleep — that they actually reported lower levels of impulsivity compared to children who did not meet any recommendations. We also found that when children met the screen time recommendation as well as the sleep recommendation they scored more favourably on all the dimensions of impulsivity that we assessed compared to children who did not meet any recommendations. 

How did you define impulsive behaviour?

We used a few different measures to assess children’s impulsive behaviour. So, these assessments tapped into a child’s tendency to not finish tasks, to their inability to delay gratification, to their tendency to blurt out things or their tendency to act rashly in negative and emotional and positive emotional states. 

That’s interesting. I have an 11-year-old and I can see that in her but I can see that in me too when I don’t get enough sleep. I’ve read reports about studies where adults are also more likely to make impulsive purchases after periods of less sleep. So, you’re seeing the same sort of things in kids?

Exactly. I think that’s a good point because you know we’re seeing this in kids but we also behave in a similar way when we’re adults too. When we don’t get enough sleep, we make poor decisions. We’re cranky. We’re moody and we’re not thinking properly. Although the study was specific to children, we can see it in our own behaviour.

You made the point of identifying this as recreational screen time. Is there a difference between recreational screen time and educational screen time?

Absolutely. When we refer to recreational screen time we’re talking about how much time children spend behind their screens when they’re watching television, when they’re video chatting, when they’re playing video games, when they’re on social media platforms… things like that versus educational purposes. A child might be on their computer but they may be completing an assignment. They may be researching a topic throughout the day. A child might go on the Internet within their classrooms and that’s OK.

I wonder if there’s a difference between the kind of recreational time that’s spent playing video games versus being on some chat or being on Facebook or Twitter?

That’s a great question. So, in our study we only looked at just time spent in recreational screen time but we have a few studies on the go now looking at the types of recreational screen time that children are engaging with that differentiate. So, when they’re on social media platforms, when they’re playing video games and then when they’re playing violent video games or watching mature videos  and how they relate to different outcomes. It’s a really, really good question. I think that’s the direction where a lot of researchers are heading. We know, generally, screen time and the outcomes associated with excessive amounts of screen time. But, what about when they’re spending you know certain amounts of time on their screens when they’re on social media vs. a television watching things like that? 

Did your findings surprise you at all?

There were a couple surprising findings. The first is that only 5 per cent of the population in our study met all three movement behaviour guidelines, which is very low. And another surprising finding is that physical activity did play an important role in the link between physical activity and impulsive behaviour but it was actually the screen time and sleep that was most beneficial or had the strongest association with lower levels of impulsivity.

Did the timing around sleep matter? Did kids have to get to bed before midnight or 10 p.m.?

So, the timing is 9 to 11 hours of sleep. We weren’t asking children ‘what time did you go to bed and what time did you wake up?’ So, as long as they accumulated 9 to 11 hours then we classified them as meeting the guidelines. 

What advice do you have for parents?

We have to be mindful of our behaviour. When we’re asking kids ‘ok, we’re gonna restrict your recreational screen time to two hours a day.’ If we’re asking them to do that then we ourselves have to be off our screens and engaging. If we’re saying that there’s no technology or devices allowed in our bedrooms — then parents will come to me and say it’s really hard when I’m telling my child that they’re not allowed any devices in their bedrooms but yet I’m bringing my phone in and they’re calling me out for it. 

So, I think although definitely challenging, we have to start somewhere. Creating healthy bedtime routines centred around screen time and sleep is obviously beneficial. So, saying that children aren’t allowed to be on any devices one or two hours before bed — that allows the children to prepare for bed. They’re getting ready to sleep. When they go into the bedroom they’re not tempted to touch any technology because their bedrooms are tech free zones.