Photo: De Agostini Picture Library/De Agostini/Getty Images
Welcome to Am I Dying, a column that hopes to save you from your late-night WebMD spiraling. You can email us your hypochondriac questions at firstname.lastname@example.org.
I’m no dummy. I know, I know that staying up at night reading garbage tweets on my phone in the dark is bad for me, on a number of levels. I have never finished one of these scrolling sessions happier, more optimistic about the state of the world, or readier for sleep. So I know I should stop. But let’s say I didn’t, or couldn’t — how badly am I damaging my eyeballs in the meantime? It’s a given that my brain is toast, but can I at least trust that I’ll still be able to see my phone ten years from now? Plus, what’s this I read about transient smartphone blindness??
Blue light — a particular wavelength of the LED-light given off by our phones and computer screens, which is typically otherwise white — probably isn’t great for us. That much is true. Blue light is thought to disrupt melatonin at higher levels than other wavelengths, which in turn can mess with our circadian rhythms. This can be a bad thing, though it all depends on how it’s used; blue light can be used to treat sleep dysfunctions, too. All of which is to say: looking at your phone before bed might inhibit your ability to get a good night’s sleep. But it sounds like you kind of knew that.
As to blue light’s direct effect on the eyes themselves, I turned to Dr. Ann Ostrovsky, an ophthalmologist at NYU Langone Health. She tells me that there’s a lot we don’t know about the effect of blue light on the human eye, because the few studies that have been done were done on animals, with concentrations of blue light far and above what a human is exposed to when, say, night-reading tweets. And that “transient smartphone blindness” study you referred to? It was a case study of two people, and refers to the phenomenon in which people looking at their phones in the dark with one eye closed experienced a very temporary gap in vision as the phone eye adjusted to the dark. Much less worrisome than the name indicates.
While we may not be exposed to all that much blue light broadly, it’s true that we are exposed to more at night — which does make it riskier (however marginally) to stick your phone screen in your face at night. “At nighttime, our pupils are larger, because we have less ambient light. So if our pupil is larger, that’s a bigger aperture for light to come in,” says Ostrovsky. “If we assume there’s a bit more blue light coming in because of the pupillary size, and if we knew blue light in the quantities we’re getting from our phones was damaging, all that would tell us is that we may be getting a bit more blue light to the retina.” So that’s a lot of if’s.
And while it remains possible that prolonged exposure to blue light could have some cumulative negative effect we’re not yet aware of, Ostrovsky says it would have to be pretty slow-building. “We’ve been using cell phones now for years, and if there was something that was acute and cumulative and rapid, we would have seen something by now,” she says. “If there is [a cumulative effect], it’s very slow, and it’s something that would accumulate over decades rather than years.” But again, that doesn’t mean you’ll go blind in your 60s: there are still a lot of if’s.
Of more imminent, frequent concern to eye doctors than blue light-based retinal damage is ordinary, irritating dry eye. When we’re looking at our phones, we tend to focus so much that we blink less than usual, Ostrovsky explains (depressingly). Decreased blinking rates lead to an evaporation of liquids from the surface of the eye, which leads to dry eye, the symptoms of which include irritation, tearing, blurry vision, and eye strain. For older folks who are less able to focus automatically (and who thus bring their phones ever closer to their faces), the risk of eye strain only heightens.
But back to that one-eyed thing for a second. I, too, read my phone in bed at night with one eye closed. Because I like to get extra credit, I asked if my doing so might in fact be a way to protect myself … one eye at a time … from both strain and blue light. “I’m not sure that’s a thing,” she said, before admitting that she occasionally does the one-eyed nighttime scroll herself. In any case, she didn’t seem to think that doing so was making anything much better or worse for us. “As far as I know, there’s no scientific reason why, if you have a healthy ocular system, you should see better with one eye than the other,” she said. “I think if you’re laying down on your side it’s probably just easier.”
You know what would be even easier, and even healthier? Closing both eyes. Ahhh. I feel better already.