Blue light before bedtime can make it harder to sleep, and the screens on phones, computers, and televisions send out plenty of blue light. This is all true. But if you're focused on blue light as a major problem affecting your sleep or your eye health, it's time to look at it from another aspect.
As Philip Yuhas, a professor of vision, writes at The Conversation, blue light isn't a uniquely technological evil. It's part of sunlight, and your eyes are exposed to plenty of it all the time. You're fine. There are studies in mice that have found blue light can damage their eyes, but mice are nocturnal creatures (夜行动物) whose eyes are different from ours. The pigments (色素) and the lenses (晶状体) of our eyes actually block blue light fairly well—so in a sense, we already have built-in blue blocking protection.
Adding more protection isn't likely to help, though. You can buy glasses and screen filters (滤光片) that block blue light, but Yuhas points out they are probably a waste of money: these products do not block out much blue light. The leading blue-blocking anti-reflective coating, for example, blocks only about 15% of the blue light that screens send out. You could get the same reduction just by holding your phone another inch from your face.
The American Academy of Ophthalmology doesn't recommend blue-blocking products, either. Instead, if you're concerned about your eye health or your ability to get to sleep on time, you already know what to do:
Put the screens away at bedtime. Read a book or find something else to do. While you're using screens take a 20-second break every 20 minutes to look at something 20 feet away ( the" 20-20-20" rule ). If you get dry eyes when you look at screens for a long time, use eyedrops labeled artificial tears.
