As part of our Biohacking Masterclass Series, we will explore a number of different techniques and practices to improve your daily performance. This series will range from obvious subjects like exercise and nutrition to fringe subjects like breathing techniques and sleep hygiene. Consult your physician before implementing any of these topics; we are here to educate. We are not your physician. Note: This post may contain affiliate links to the products we use.
How you read before bed matters
When people struggle to fall asleep, it seems like the first few recommendations typically include reading a book before bed. Historically, there was likely very little reason to question this suggestion. After all, books themselves were only ever paper bound in one way or another. Today, however, that recommendation poses more risk to healthy sleep than most people care to recognize.
The advent of “e-readers” like the kindle or Apple iPad (and its abundance of apps) have changed the way ‘reading’ interacts with sleep.
Is there a difference between a traditional paper-paged book and new-age e-readers?
Fortunately, the impact of sleep on mental and physical performance has gained increased attention over the last decade. Many researchers are now evaluating the effect novel technology has on our evolutionarily hardwired sleeping patterns.
In a study evaluating the effects of e-readers and traditionally printed books on sleep, researchers discovered several differences.
When participants took up an e-reader like a kindle, which emits light in some form, they eventually averaged significantly increased sleep latency, taking more than 10 minutes longer to fall asleep than their paper counterparts.
Secondly, these screen-readers had significantly less REM sleep than those reading paper books.
Thirdly, those reading on a light emitting device were associated with less evening sleepiness and more morning sleepiness. The researchers further conclude their recovery period to truly “wake up” was several hours later in the morning than those reading printed books. 
While taking longer to fall asleep and increased morning sleepiness are easily digested findings, what exactly does less REM sleep mean?
The REM sleep stage generally functions to reinforce old neural connections and strengthen new connections in the brain (i.e. this stage is relevant to learning and integrating newfound knowledge into your brain for later use in problem solving, critical reasoning, and more).
If you’re getting less REM sleep, your rate of learning and overall mental and physical improvement could be inhibited.
We are strong proponents of reading. We also are consistent pre-bed readers. While this article and highlighted study target the downsides of reading on a light emitting device, it also shows a positive trend when reading on a traditional paper-printed book.
As we’ve written in previous articles, light is an extremely powerful mediator of your body’s circadian rhythm. Be disciplined and diligent with the hues of light you expose your eyes to before bed. Novel technology can be used to your advantage with the placement of colored LED lights (turned to red hues) before bed. If you have a kindle or other light emitting device that you use to read, consider limiting its use to daylight hours and save a real book for before bed.
If you’re interested in learning more about the most powerful regulators of your biological sleep clock, read our write up on temperature, on light at night, on light in the morning, and our complete sleep guide.
- Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc Natl Acad Sci U S A. 2015;112(4):1232-1237. doi:10.1073/pnas.14184901124