COMMENTARY

Does Using an e-Reader Before Bed Ruin Your Sleep?

Aaron B. Holley, MD

Disclosures

March 29, 2016

I like to read in bed as part of my evening routine. For years now I've been using an e-reader. I can download a new book anytime I need one, I can switch back and forth between books, and the bedroom isn't cluttered with paperbacks or hardcovers. I love my e-reader. I also love my sleep, and as a board-certified sleep physician, I know how important sleep is to quality of life, health, and cognitive and physical performance.[1]

Authors of an article recently published in the Proceedings of the National Academy of Sciences suggest that using an electronic device before bed is harmful.[2] The title, "Evening Use of Light-Emitting eReaders Negatively Affects Sleep, Circadian Timing, and Next-Morning Alertness," says it all. No eating or alcohol before bed; now no e-reader either?

The authors randomly assigned 12 healthy young adults to two different exposures: reading an electronic book for 4 hours before bed versus reading from a non–light-emitting source (ie, a printed book). All participants were subjected to both conditions in a random order. In the e-reader group, melatonin levels were suppressed by 55% and dim-light melatonin onset was 1.5 hours later when compared with the printed-book condition. Sleep-onset latency was 10 minutes longer in the e-reader group, and they had less rapid-eye movement (REM) sleep and were less alert the following morning. Yikes!

A few caveats are in order, though. First, I'm not sure how many people use an e-reader for 4 hours before bed, all the while holding it 30-45 cm away from their face (the distance that was specified by the investigators). I know I don't. The authors make the point that teens often get 4 hours of cumulative artificial light exposure leading up to bedtime, but this includes exposure to television and other sources that may not have the same potency. Second, total sleep time and non-REM sleep were not different between groups. Last, there was no impact on sleep efficiency.

In summary, the effects that the authors found are probably exaggerated. That said, this study clearly shows that using an e-reader causes a circadian rhythm phase delay. This is concerning. Circadian disruption and misalignment can significantly degrade health and performance.[3] Even if your patients don't read their e-reader for very long, shorter times when added to television, computers, and smartphones likely add up to several hours of pre-bedtime artificial light exposure. Teenagers, already physiologically delayed and forced to wake up earlier than their circadian rhythm would prefer, could be particularly vulnerable. I've advocated in the past for a comprehensive, protocolized sleep history for all patients presenting to a sleep clinic.[4] Perhaps it's time to add a question that specifically addresses e-reader use before bed.

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