By now you're probably aware of the perils of using your phone before bed — you'll take longer to fall asleep and you won't sleep as deeply as you would have if you logged off a few hours earlier. Now, a new article in the the New England Journal of Medicine outlines another possible, if oddly specific, risk of late-night phone use: transient smartphone "blindness."
Before you freak out, please note that this so-called "blindness" is not, like, actual blindness (without the air quotes).
The letter is based on the cases of two women, a 22-year-old and a 40-year-old, who had both been experiencing temporary blindness in one eye. Both women's symptoms occurred a few minutes after using their phones in the dark, lying on their sides, looking at the screen with only one eye (the eye closer to the pillow was closed).
Their doctors believe that, after the women used their phones in the dark, their eyes were out of balance — the eye that had been viewing the screen was accustomed to light, while the one against the pillow had already adapted to the dark. So, when they put their phones away, the women experienced a lack of sight in their "light-adapted" eye, which their doctors referred to as "transient smartphone blindness." It lasts just a few minutes (probably as long as it takes for the eye to reset) but can certainly be alarming in the moment.
As unsettling as this is, you probably don't need to worry about it. After all, the doctors' concerns are only based on two patients' cases, which is not enough to prove this is a real phenomenon. It only applies to people who look at their phones with one eye, so it's also unclear how many people will actually experience this. Plus, even if it does happen, it seems to be more in the category of "weird body phenomena" than a sign that something's wrong.
Still, if you just have to check Instagram before hitting the hay, do it while lying on your back, with both of your eyes. Or, you know, just read a book. Your eyes — and your sleep — will likely benefit.