Screen Use And Mental Health Part 3: Sleep And Smartphones

Last time I reviewed how tv and video games can affect sleep. Smartphones need their own article.

Smartphones are potentially more of a problem because unlike other devices they can alert a sleeping person to incoming calls/texts/messages. In fact, at least 30% of teens report being woken up during the night by their phone. In addition, I suspect phones are more of a problem because they are incredibly stimulating and their use is difficult for parents to monitor. Whereas a TV or video game will likely wake the family, smartphones can be used at any time in complete privacy.

A big problem with the research is that about 20 years of phone use studies are potentially not that relevant anymore. Specifically, phones have changed in the past 10 years. A lot! Older research actually gave support to the idea that phones weren’t too disruptive; Something that is difficult to imagine given their current form. They are now far more immersive, difficult to monitor, provide immediate gratification, and give off blue light. As such, they have the potential to affect sleep in multiple ways.

Smartphones Are A Major Problem For Teens Because:

  1. They can be used late at night, without parents being aware.

This shifts sleep to occurring later

  1. Smartphones also wake teens up from sleep when people text or use social media.

This interferes with the sleep process

  1. They often emit blue light, and the screens are bright

This interferes with the circadian rhythm

  1. They offer immediate gratification and are exciting to use

This increases arousal which makes falling asleep more difficult

The Research

The more recent data has shifted this discussion and provides a lot of evidence that smartphones are a BIG problem. They are likely more disruptive to sleep than any other device. In fact, even frequent brief checking of smartphones has been shown to affect sleep. A recent meta-analysis study showed that adolescents with access to portable screens (phones and tablets) close to bedtime had a 79% higher chance of sleeping less than nine hours than those without that access. This makes sense because these devices can be carried around and used in bed with ease.

One lab decided to look at whether teen sleep has been disrupted by the newest generation of screens. You can find the article here. They examined various outcomes, one of which was the likelihood of sleeping less than 7 hours, since this is sometimes used as an indicator or poor sleep. They looked at sleep data from 1991 to 2015 using two different datasets, which involved around 500,000 adolescents. This is a huge number! All of the data was self-reported, meaning that their sleep was rated on a questionnaire rather than actually monitored in a lab. As such, it could be quite inaccurate and involve under or over-estimates. You can actually see this in the data, as the two different datasets they used varied by up to 10% on sleep estimates in some years.

What Did They Find?

They found that 2013 was a key year. They showed that from 2013-2015 around 20% more adolescents started to experience insufficient sleep. Previously the data showed that around 35% teens slept less than 7 hours per day, and this jumped to around 43% of teens after 2013. What happened around this time? Their belief is that smartphones sufficiently saturated the market to interfere with sleep on a mass scale. But the REALLY cool thing these researchers did was look at whether certain types of screen use increased the risk.

What Type Of Screen Use Is Associated With Poor Sleep?

They looked at the odds that a certain activity will be associated with getting less than 7 hours sleep per night. They examined the effect of “new media screen time” (i.e. portable electronics like phones, social media, and reading news online), other screen time (e.g. TV), and other factors (e.g. hanging out with friends, exercising). What did they find?


The Main Takeaway

It’s clear that too much new media screen use, homework, and having a paid job are all associated with too little sleep. And it’s clear that teens are sleeping less and less each year. What’s changed in the past 25 years? Well, homework and number of teens with paid jobs is pretty much constant. Time spent on TV and video games is much the same. These things haven’t really changed in many years. But guess what has increased, especially in the past 5 years? Smartphone use. They concluded that this is good evidence of a strong association, and possibly demonstrates that electronics may cause sleep problems.

This research does show compelling evidence that new media time (phones, social media) is related to worsening sleep among teens. Their conclusion is essentially that smartphones are contributing to a massive increase in sleep-related problems.

Some Other Takeaways

Again, when I discuss these issues and use the term “new media”, I am referring to smartphones and tablets. These are the devices with which many teens are using for social media and the internet. These are the only devices associated with the jump in worsening sleep among teens.

  • New media screen use is not associated with better sleep! This is contrary to what many teens will say. If you use screens more than three hours per day you are around 1.2 times more likely to experience less than seven hours sleep. While that doesn’t sound like a lot, that’s actually a big deal. In real numbers, that could affect hundreds of thousands, perhaps millions, of teens’ sleep. There was a strong correlation between new media screen use and sleep problems. Specifically, the more hours of screens that a teen used the greater their chance of sleeping less than seven hours in a night.


  • If you think about kids who have a job or have a ton of homework, you know how stressful that can be. It’s a lot of work, and may involve many late nights. Well, this research says that if you use screens more than three hours per day, or social media/news every day, your risk of getting less than seven hours of sleep is equitable to kids who have jobs or more than 10 hours of homework per week. You may not think of screens as having the same effect as other stressful events, but they do. I wonder what the effect of both would be?


  • A question I asked in a previous article was whether online social interaction is different to in-person social interaction. With regards to sleep, this evidence suggests that there is a difference. Anything online for more than three hours per day, or daily social media use, is associated with poor sleep. Yet in-person social interactions don’t affect sleep at all.


The current state of the research is generally limited, but I expect in the next few years we will learn a lot. The data is clear that screens of all types are associated with poorer sleep. However, in the past five or so years there seems to have been a shift for teens who are now sleeping less. The rapid development of smartphones is strongly associated with this problem. “Screen use” is more and more becoming synonymous with smartphone use. It is suggested that using screens for more than 2-3 hours per day may increase risks to sleep. If you’ve ever tracked your own usage (with apps like Moment), you’ll know that it can be quite easy to exceed this amount of time. The more general literature says that the time of screen use is very important, with evening use seemingly being most problematic. Although I am focusing on teens, this data surely applies to adults too.  Thanks for reading!

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