More on the Science of Screens and Sleep

screens at bedtime

Our nighttime screen reading habits have a profound effect on our sleep habits — it’s such an interesting (and sometimes personally relevant topic) that I keep coming back to it.

Lots of exciting research on this topic, from Harvard (via BBC, “E-books ‘damage sleep and health,’ doctors warn”),* and the British Medical Journal (via Quartz, “More Evidence That Smartphones Need to Stay Out of Bed”) suggests that the combination of blue light and time-wasting is simply making it harder and harder for us to fall asleep at night.

Other research is suggesting that what we do on screens at bedtime is also to blame. From Nature, “What’s Keeping you Awake at Night?” —

“maybe it’s not the screen you’re looking at itself; maybe it’s what’s on the screen that’s the problem. Several studies have reported an increase in stress levels induced by late-night texting, which can trigger insomnia and disrupt sleep patterns. A preliminary study from University of Texas Pan-American reported higher stress levels and poorer sleep in students who texted or went online within two hours before going to bed. Another report stated similar findings when it came to active screen behaviors, like emailing or playing a video game, but no difficulties in those who just watched a movie on their laptops. Thus, the problem may be more linked to the type of activity you use your computer for, with active screen behaviors causing higher arousal rates before bed.”


Even more interestingly, our brains are more awake without us necessarily feeling more awake. The numbers from survey after survey seem to indicate that we are spending increasingly more time with our devices at bedtime in a myriad of activities such as reading**, browsing, watching. I wonder, for example how much screen size might play a role — are smaller screens less bad than tablet or computer screens? And if so, how much less bad? And how many hours of screen-free time do we really need?

The Atlantic (“How Smartphones Hurt Sleep”) delves into more of the correlations between our sleep and our nighttime screen behaviors. And there do seem to be rather serious health-related reasons — increased risk of obesity, diabetes, cancer — for us to reduce our screen time at night (via Huffington Post, “Reading on Screen Before Bed Might Be Killing You” … ugh, that title gore, but still).

While there are options for filtering out some of that nighttime screen brightness (such as this one or this one), it still remains to be seen just how much any of this alleviates the problem. Especially this option for blue light filtering for iPhones and iPads; I’m torn between being intrigued and awfully suspicious of gimmicky marketing.

Maybe sometimes we really do need to get on our devices before bedtime, but better still would be a change in habits, (from CNET: “How to Stop Sleeping with Your Phone”). Setting a daily routine and keeping the phone and tablets and computer far away from the bed are my favorite suggestions; remember when Oscar Wilde said that the only way to get rid of temptation is to yield to it … better keep tempting devices at least out of arm’s reach.

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kindle paperwhite reading at night

* I wondered about eInk readers such as Kindle Voyage and Nook GlowLight, thanks Gigaom for bringing up this topic: “Do e-readers really harm sleep? Depends what you call an e-reader.” Definitely will be of interest to Kindle users such as myself:

“The key problem with this study and the more alarmist stories that followed, is that when it says “e-reader”, it means “Apple iPad”. An iPad at full brightness, no less. When I hear “e-reader”, I tend to think “dedicated e-reader” — an e-ink device without a backlit screen — rather than a multi-purpose tablet. And there’s a big difference.”

Keep in mind the research quoted was from 2010–2011, before the newest generation of eInk readers. Those newer eInk screens are probably less of a sleep deprivation risk, although ‘probably’ is only based on what we know from how the eInk screens function with reflected light: “Rather than lighting the screen from behind, illuminated e-ink e-readers are ‘front-lit’ and use small LEDs around the screen, pointing inward rather than outward, to cast a glow over it (the Paperwhite channels this through ‘light guides’ to illuminate evenly). This is more like looking at an earlier Kindle in a lit room, than it is like looking at a light shining directly into your eyes.”

** Also this from some Stanford sleep research via Wall Street Journal, “Science of Bedtime Reading: Can Tablets and e-Readers Keep You Up?” Although it makes for good common sense to limit our bedtime … sometimes it’s just too enjoyable not to: “For starters, Dr. Kushida explained that reading itself can be an issue. ‘Following a consistent schedule, reading for a set period of time and turning out the light is perfectly fine, as long as you’re not sleepy during the day or have problems with insomnia,’ he said. ‘But if a person does read and finds that it delays their ability to fall sleep, we would tell them to not read.’” Science is no fun sometimes.


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I run the ThinkLab at the University of Cambridge, and research digital habits, productivity, and wellbeing.

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