Why the light from your smartphone is keeping you up at night, and what to do about it

Takeaway: Exposing your eyes to too much blue light (from your smartphone, tablet, or computer) before bed is detrimental to your sleep. The fix: pick up a pair of blue-blocking sunglasses, limit your exposure to blue light before bed, and ritualize shutting off your devices past a certain time every night.

Estimated Reading Time: 4 minutes, 12s.

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Exposure to blue light affects your sleep

Exposure to blue light before you go to bed significantly affects your sleep quality, because it prevents your body from releasing melatonin, a chemical in your body that helps you sleep. Unfortunately, all of those electronic devices you use before bed (your tablet, cellphone, computer, and TV included) bombard you with an incredible amount of blue light, which can significantly hamper your sleep quality if you’re not careful.

When I chatted with my buddy Ari about sleeping hacking the other week, one of his top suggestions for something I should experiment with surprised me: that I should wear a cheap pair of blue light-blocking sunglasses a couple of hours before I went to bed.

I was a bit skeptical, so I decided to wear them two hours before bed for a few weeks to see if they produced any results (besides making me look like a doofus). But back to that experiment in a second.

Pretty much every study that has analyzed blue-blocking sunglasses has found them to be incredibly effective in helping you sleep. Take these two that I stumbled upon recently:

  1. One study had participants wear “either blue-blocking (amber) or yellow-tinted (blocking ultraviolet only) safety glasses for 3 h prior to sleep”, and “[o]nly individuals who reported sleep difficulty were included in the study”. Even though the study used a small sample size, what they found was incredible: participants who wore the blue-blocking glasses observed more than a 50% increase in the quality of their sleep, and they were 40% happier after they woke up.1
  2. Another study measured the actual melatonin levels produced by participants who wore blue-blocking sunglasses and regular sunglasses (for comparison). Participants who wore regular sunglasses had their melatonin levels drop 46% (not a good thing), while participants who wore the blue-blocking glasses had a 6% increase in melatonin production (a very good thing). But the results are even better than they sound: participants wearing the blue-blocking glasses were blasted with 25% brighter light compared to the control group!2

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Here’s what to do about it

In hacking around with my sleep, I noticed something fascinating: I could literally use all of my devices up until the moment I went to sleep without any adverse effects, as long as I wore my blue-blocking sunglasses. I usually don’t like to stare at shiny screens late into the night, but for the sake of this experiment I was able to do so without any adverse effects with blue-blocking sunglasses on.

It might sound crazy, but blue-blocking sunglasses will help you fall asleep faster, and then sleep better throughout the night. You’ll look like a total doofus wearing sunglasses indoors, but if you want to look at bright, blue light-emitting screens late into the night, you should throw on a pair of blue-blocking sunglasses so you don’t compromise your sleep. And you can order a pair for $10 off of Amazon, so you really have no excuse. The Harvard Medical School recommends avoiding blue light 2-3 hours before you go to bed.3

Here are a few other ideas on how to eliminate blue light from your nightly ritual, and how to use blue light to your advantage:

  • Limit your exposure to energy-efficient lighting before bed. In addition to the LED screens in your electronics, energy-efficient lighting emits a lot of blue light, which can also compromise your sleep.
  • Expose yourself to a lot of blue light during the day. Exposing yourself to blue light during the workday has been shown to boost your alertness, performance, and sleep quality.4
  • Ritualize shutting off your devices past a certain time. When I’m not experimenting around with different routines, I’ve created a habit of turning my phone on airplane mode between 8pm and 8am (I wake up at 5:30). This forces me to be more mindful and slow down before bed, but it also has the added benefit of helping me sleep better.
  • Download f.lux (free). F.lux won’t completely eliminate how much blue light your computer monitor emits, but it will change the colour temperature of your screen after the sun sets in your location, which will reduce the amount of blue light your screen emits, helping you sleep better.
  • Invert the colours on your iPhone/iPad. This will make your screen darker, so it emits less white and blue light. Navigate to Settings -> General -> Accessibility -> Accessibility Shortcut -> Invert Colors. Now, whenever you triple-tap your home button, the colors on your device will invert.

The bottom line: exposing your eyes to too much blue light before bed is detrimental to your sleep. The fix: pick up a pair of blue-blocking sunglasses, limit your exposure to blue light before bed, and ritualize shutting off your devices past a certain time every night.

Purple smartphone image source.


  1. Source: http://www.ncbi.nlm.nih.gov/pubmed/20030543 

  2. Source: http://www.ncbi.nlm.nih.gov/pubmed/16842544 

  3. Source: http://www.health.harvard.edu/newsletters/Harvard_Health_Letter/2012/May/blue-light-has-a-dark-side/ 

  4. Source: http://www.ncbi.nlm.nih.gov/pubmed/18815716 

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