Sensible advice for aches, pains & injuries


Sad, bad news about e-books and sleep

Paul Ingraham ARCHIVEDMicroblog posts are archived and rarely updated. In contrast, most long-form articles on are updated regularly over the years.

Well this sucks: reading backlit devices like iPads before bed probably hurts sleep, according to a new study. A dozen people were studied for 14 days, half reading regular books and half reading backlit e-books each evening. Blood tests, brain waves, and other measures showed that the e-book readers were less sleepy, took longer to fall asleep, shifted their circadian rhythm later, were less alert the next morning, and produced much less melatonin (the time-to-go-to-sleep hormone).

And any enemy of sleep is a risk factor for pain.

Reading a light-emitting eBook in the hours before bedtime likely has unintended biological consequences that may adversely impact performance, health, and safety.

Not really surprising, I suppose. But so unfortunate. E-books are one of the best things about The Future. They are the main reason I’ve bought any mobile device for almost a decade. They’ve changed my life as much as any technology ever has — like earning a living from selling them, for instance — but perhaps in worse ways than I realized.

But perspective!

Only a half dozen study subjects read e-books for four hours each evening. That’s a lot of reading. I’m lucky to squeeze in a half hour at the end of the day. And I mostly read on a well-dimmed iPad, usually with inverted colours, which probably emits an order of magnitude less light than what was studied here.

And there are also other options, like e-ink devices, or shifting the display colour away from daylight hues with like software like f.lux (sadly, unavailable on iThings). With some moderation and precautions, the risk is probably not great — or at least no greater than many other ubiquitous challenges to sleep in modern living.

Still, it’s really a shame we might have to add e-books to that list.

I’ve added this science to my main insomnia article.

“Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness”
Chang et al. Proceedings of the National Academy of Sciences of the United States of America. Volume 112, Number 4, 1232–7. Jan 2015.

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