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How Your Smartphone Messes with Your Brain—and Your Sleep

The views expressed are those of the author and are not necessarily those of Scientific American.

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It’s not the Angry Birds, streaming videos, emails from your boss, or your Facebook updates that disturb your sleep when you spend an evening staring at your smartphone or tablet.  OK, the apps can keep you glued to your screen until the wee hours, and that doesn’t help. But it is the specific type of light from that screen that is throwing off your natural sleep-wake cycles, even after you power down. In a new video from Reactions: Everyday Chemistry, a sleep researcher explains the eerie power of blue light over your brain.

Cells at the back of your eyes pick up particular light wavelengths and, with a light-sensitive protein called melanopsin, signal the brain’s master clock, which controls the body’s circadian rhythms. Blue light, which in nature is most abundant in the morning, tells you to get up and get moving. Red light is more common at dusk and it slows you down. Now, guess what kind of light is streaming from that little screen in your hand at 11:59 P.M.? “Your iPad, your phone, your computer emit large quantities of blue light,” says sleep researcher and chemist Brian Zoltowski of Southern Methodist University

The results of staring at them are tiresomely predictable. Think about that when you are tossing and turning in bed a few hours later. And tomorrow night, try shutting down earlier. Let us know what happens in your comments below, too.

Josh Fischman About the Author: Josh is a senior editor at Scientific American, covering biology, chemistry, and earth science. On Twitter, he is @jfischman, and you can email him story ideas at Follow on Twitter @jfischman.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. MGhydro 12:28 pm 05/20/2014

    There is an app called f.lux that changes your screen tone to warmer colors with time, especially in the evenings. You can adjust the timing and levels of change to your preference. It was great for me, eliminating many bedtime headaches from late work on an over-bright computer. Highly recommended.

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  2. 2. greenhome123 4:08 pm 05/20/2014

    I believe a change in blue / red light also effects plants. My house plants seem to like the light from my TV/Computer Monitor. It is a 52 inch sony LCD. It is not an LED. I’m curious if regular old LCD gives off more blue light than the new LED TVs. Does anybody know?

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  3. 3. RayCL 4:42 pm 05/20/2014

    I’ve had people warn me about this sleep disturbance issue, but could not identify with it. I usually take my MacBook Air with me to bed, and sometimes actually doze off while emailing or browsing with the Air propped against my legs. I was curious, and recalled something about automatic display dimming. Looked into it and found that indeed in low ambient light, in addition to the more obvious fact that the keyboard lights up, the screen brightness diminishes proportionately. I recall that I enjoyed the novelty of it when I first moved to Mac a few years ago, and I guess I’ve taken it for granted since then. It’s kind of subtle, and not intrusive. In any event, it’s been a sort of partly guilty pleasure to enjoy my Air for a while before I get drowsy and close the lid, set it aside and roll over to sleep. Also I often open the lid in the AM and continue where I left off the night before, when the thoughts are usually still fresh, and at times wind up getting a very late breakfast. (-8

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  4. 4. SJCrum 7:00 pm 05/20/2014

    For information, in my understanding there isn’t any affect at all that comes from light sources like the one described here. And, instead, sleep interruption occurs by people having their minds focusing too much on things that cause the brain to be too active.
    So, to prevent that after a long digital interaction, just read a somewhat boring book that causes you to completely pass out, or something like that. the bright screens cause people to think of what is on them too much at the time of needing to sleep instead.
    But, in my understanding the devices don’t affect the brain at all. It’s just mental instead.

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  5. 5. sohanj 9:31 pm 05/20/2014

    Long time ago we did not had electricity in our village in India.When gov installed the electricity many older people protested against the electricity it will make you blind. It produce too sharp light. Then not many people had eye glasses they had good eyesight. After that more and more people getting eye glasses.
    May the too much light have effect on eye sight. But I can not believe that having phone in bed room can effect sleep. There are many other reason for not having good sleep. We do not know how to sleep for one reason. Too much to eat before going to bed. Eating wrong food. Not chewing food long enough. Fix these things one can have good sleep.

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  6. 6. TonyTall 2:39 pm 05/21/2014

    It is not very helpful for a writer merely to tell us some ideas, even if they are reasonable and sensible. Are these results based on carefully controlled experiments that have passed peer review?

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  7. 7. Anonymous 4:30 pm 05/21/2014

    Some peer reviewed studies:
    Zoltowski, Brian D., Gardner, Kevin H., “Protein:Protein Interaction Networks in Blue-Light Photosensors,” Biochemistry, 2011, 50, 4-16.
    Lamb, J. S., Zoltowski, B. D., Pabit, S. A., Crane, B. R., Pollack, L., “Illuminating Solution Responses of a LOV Domain Protein with Photocoupled Small Angle X-ray Scattering,” Journal of Molecular Biology 2009, 393, 909-919.
    Zoltowski, Brian D., Vaccaro, Brian, Crane Brian R. “Mechanism Based Tuning of a LOV Domain Photoreceptor,” Nat. Chem. Biol. 2009, 5, 827-834.
    Lamb, J. S., Zoltowski, B. D., Pabit, S. A., Crane, B. R., Pollack, L., “Time-Resolved Dimerization of a PAS-LOV Protein Measured with Photocoupled Small Angle X-ray Scattering,” Journal of the American Chemical Society 2008, 130, 12226-12227.
    Zoltowski, B. D., Crane, B. R. “Light Activation of the LOV Protein Vivid Generates a Rapidly Exchanging Dimer,” Biochemistry 2008, 47, 7012-7019.
    Zoltowski, B. D., Schwerdtfeger, C., Widom, J., Loros, J. J., Bilwes, A. M., Dunlap, J. C., Crane, B. R. “Conformational Changes in the Fungal Light Sensor Vivid,” Science 2007, 316, 1054-1057.

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  8. 8. hkraznodar 5:23 pm 05/29/2014

    @SJCrum – Still a complete nutter, I see. I have yet to see any post of yours that has any references to real peer reviewed studies. The opinions that you state as if they were facts are usually so wildly wrong it is rather sad.

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  9. 9. DGeller 1:48 am 12/29/2014

    Great article! I have been using a SleepShield screen protector that blocks the blue light on my phone and iPad. It’s helped the quality of my sleep and my children’s, we are definitely guilty of using our devices before bed and even in bed.

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