Is Blue Light Really Bad for Sleep?

Dr. Mac’s Rants & Raves

Episode #169

Apple introduced iOS 9.3 a couple of weeks ago and I’ve been obsessed with Night Shift ever since. Night Shift, in case you missed it, is a new iOS feature that uses your device’s clock and geolocation services to determine sunrise and sunset at your location, then uses this information to gradually adjust the colors on your screen to the warmer end of the spectrum as darkness falls, gradually returning the colors to normal as the sun rises.

According to Apple, “Many studies have shown that exposure to bright blue light in the evening can affect your circadian rhythms and make it harder to fall asleep.”

So my obsession lately has been with finding conclusive evidence one way or the other that blue light either does or does not affect sleep patterns.

I’ve now clicked hundreds of links; skimmed myriad research papers and articles; and read dozens upon dozens of articles. A number of studies indicate that those who read with a tablet before bedtime experienced poorer quality sleep and woke up feeling less alert than those who read a traditional hard or softcover book before bedtime. Other studies imply that the blue light is bad for sleeping because it inhibits the body’s production of melatonin, a hormone that plays a critical role in falling asleep. There’s also some evidence that donning orange-tinted glasses—also known as blue-blockers—before bedtime may help you fall asleep faster and sleep better.

And after digesting it all I’m certain of three things:

  1. There is a some relationship between blue light and difficulty falling and staying asleep.
  2. There is compelling evidence that reducing or eliminating blue light for an hour or more before bedtime may help you fall asleep faster and have better, deeper sleep.
  3. I’m not taking any chances; I want it running on every screen I look at after sundown!

I’ve been running a free Mac app called f.lux, which does for Macs what Night Shift does for iOS devices, and Night Shift on all my iDevices, for the past couple of weeks and I’ve noticed two things: I’m ready to go to bed a bit earlier, and I awaken feeling more refreshed and less groggy/tired than usual.

f.lux Prefs

f.lux’s menu and Preferences window provide more control over screen color and temperature than Night Shift.

A comparison of f.lux off (left) and f.lux on (right) on my 2014 MacBook Pro.
(Click or tao for a larger version)

I suspect at least part of this is due to confirmation bias (thanks Mac Geek Gab): Because I expected (and hoped) Night Shift and f.lux would help me fall asleep faster and sleep more soundly, they did.

But I don’t care if I’m biased. I seem to be sleeping better and falling asleep earlier, and I don’t know of any downsides or gotchas. So, intend to run Night Shift and f.lux on all my supported devices until the end of time. (For what it's worth, my first generation iPad mini doesn’t support Night Shift, so I don’t use it after sundown anymore.)

Your mileage may vary, but I recommend at least giving Night Shift and/or f.lux a try.


And that’s all he wrote…