Are Screens at Bedtime Bad For Us? Yes.

File this one under Things We Know Really Should Stop Doing (via NPR: “One More Reason To Reach For A Paper Book Before Bed”), staring at light-emitting (specifically shorter wavelength blue light) screens before bed is bad for our health:

screens before bedtime = bad

“ ‘We knew that light in the evening affects circadian rhythms and affects sleep and alertness,’ Chang says. ‘But we wanted to test if light from light-emitting devices, such as e-readers, which were gaining in popularity, would have the same effect if people were using them to read before bedtime.’ So the researchers asked 12 healthy young people to spend a couple of weeks in a sleep lab. For five nights, they read what they considered to be relaxing material on an iPad for four hours before going to sleep. For another five nights, they read the same kind of material from books made of paper.

Based on the findings and others, Chang recommends that if people want to read before bed, they should consider devices that don’t emit light — or just pull out an old-fashioned paper book.”

(I wonder how many of the participants in the print book reading study snuck glances at their devices while reading … but that’s a different topic for another day).

Too much nighttime screen time (unsurprisingly) makes us less alert during the daytime, causes difficulty falling asleep at night, and generally wrecks havoc upon our circadian rhythms. In more specific terms: “light from the screens will increase alertness at the very time you should be winding down, which can delay people’s bedtimes. This exposure will then prolong the length of time it takes to fall asleep, which delays the circadian rhythm, which reduces the amount of melatonin (the sleepy-making hormone) that the body produces. It can also delay and reduce the amount of REM sleep, and finally it will negatively impact awareness the following morning” (via Wired UK, “Screen Reading Before Bed Can Ruin Your Sleep”).


On the other hand, there are also these really dumb-looking-but-maybe-effective orange glasses (via The New York Times, “Can Orange Glasses Help You Sleep Better?”) which could help counteract those deleterious, melatonin-inhibiting effects of blue light emitted from screens. Or … could we just not?

The NYT article has lots of interesting points, definitely worth a read. I’d never heard of the more general applications for blue light blocking —

“LEDs are also increasingly popular as room lights, but “warm white” bulbs, with less blue, tend to be a better choice than “cool white” for nighttime use. The lighting company Philips also makes a bulb, called Hue, that can change the intensity of its component colors via an app, and GE last month announced a reduced-blue LED bulb, meant to be used before bedtime.”

Granted, people are probably more and less sensitive to these light sources than others, but in terms of practical tips: “Short of cutting out all evening electronics, experts say, it’s advisable to use a small screen rather than a large one; dim the screen and keep it as far away from the eyes as possible; and reduce the amount of time spent reading the device.”


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

tyler shores cambridge

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