This is What Happens to Our Brains When We Look at Screens Before Bed

During most of human existence, people had to move in tandem with the rising and setting of the sun. We came to understand that dawn cued us to work, to interact, to get up and go, and the dark was our call to lie down and sleep.

While ever-growing technologies now allow us to be surrounded by light even in the wee small hours of the mornings, much of our brains are stuck in the Dark Ages. Indeed, our brains physically remain much akin to those of early Homo sapiens, which is one reason we suffer for the desire to stay up late as the sun goes down.

Multiple studies have linked exposure to light at night, especially by way of third-shift jobs, to heart disease, diabetes, cancer, depression and obesity. While a variety of theories stand to explain these individual ailments, our primary understanding of why nighttime light does us harm has to do with the fact that exposure to light suppresses the secretion melatonin, a hormone that helps manage our circadian rhythm. This is bad news, as the unnatural suppression of most any naturally-occurring hormone (like insulin, for example) can lead to chronic and serious disease states.

But is that the end-all, be-all of the story? What of the fact that light runs across a spectrum — are all forms and colors equally bad for our health?

The science tells us: no. Blue light, which is primarily associated with the short-wavelength-enriched glow of our favorite electronic devices, fluorescent lightbulbs and LED lights, has a more powerful and immediate affect on our bodies than other hues. That’s why researchers, who note that the bulk of blue light we experience after nightfall comes from illuminated screens, have been keen to study how our favorite electronic devices affect our health.

In one instance, a 2014 study compared the effects of reading from an electronic device to the act of reading from printed pages. The results showed that participants who read from the devices subsequently experienced lingering alertness around bedtime; struggles to fall asleep; and less REM sleep, which happens to be a restorative phase during which we dream. After eight hours of sleep, individuals who read from light-emitting devices reported feeling drowsier than their print-reading counterparts, and had more difficulty waking up.

Anne-Marie Chang, one of the Harvard neuroscientists in charge of this study, noted that “all participants had to stop reading and turn off the lights at exactly 10 P.M., even if they did not feel sleepy. At home, I would expect people do not have the motivation to turn off their devices and go to bed, so they would stay up [even longer] and experience even more circadian delay and shorter sleep times.” This, according to Chang, means that the effects of electronic devices on sleep “could actually be even greater” in real-world scenarios.

The people most likely to be affected in such scenarios are teenagers — individuals whose circadian rhythms are already in flux, and who statistically feel more awake later at night (and have done so long before the invention of the iPhone). This means that an already sleep-deprived teenager who has to rise early for school can experience further lethargy and difficulty focusing simply because she watches TV before bedtime.

Still, no matter your age, there are ways to manage the the effects of manufactured late-night light:

  • Make sure you take in lots of bright light during the daylight hours, naturally reinforcing your body’s circadian rhythm.
  • Dim your devices as the sun starts to set.
  • Stay away from bright electronics two to three hours before bedtime.
  • Slip red light bulbs into the lamps you use most frequently around bedtime. (Red light is the least stressful color to circadian rhythms.)


Sonia Minwer Barakat Requ

Thanks for sharing

Siyus Copetallus
Siyus Copetallus3 years ago

Thank you for sharing.

Geetha Subramaniam

And all this while I thought it was the 4:00 tea that kept me away. I had started reading online a few months ago. Not the most comfortable way to read an book... Still it was there online.

Thanks for article and Thanks Peggy B for the links to get flux.

James Maynard
James Maynard3 years ago

Guess I'm just the odd duck as none of this seems to have any effect on me.....I hit the pillow and am usually out until daybreak....or just before when my cats start howling for me to get my lazy self up and feed them - ha ha ha!

Alexander P.
Alexander P3 years ago

Peggy B., I've been using "F.lux" for a long time, and I also recommend it!

Iskrica Knežzevic

thank you

Angela AWAY
Angela K3 years ago

Thank you

Jim Ven
Jim Ven3 years ago

thanks for the article.

Marie W.
Marie W3 years ago

Get flux.