The sales pitches tempt: Blue-light-blocking glasses are supposed to protect eyes from the effects of short-wavelength light emitting from our smartphones, computer screens and LED lights. Given how much time we spend on our devices, this sounds like a smart investment, right? After all, eye strain is a real issue and can lead to poor sleep and even eye diseases. The glasses can cost $15 all the way up to several hundred dollars. But do they work?
Elizabeth Esparaz, an ophthalmologist （眼科专家） based in Cleveland, Ohio, says the science that manufacturers share as they promote these glasses can be confusing. For starters, blue light is not just about tech devices, and it's not always bad. "The sun emits a much higher intensity of blue light than human-made devices, of course, and it's actually beneficial, " says Dr. Esparaz. It helps our mood, alertness and sleep-wake cycle.
The problem is blue light at night: It contains the release of melatonin. "Melatonin helps regulate our circadian rhythms （生理节奏）and makes us sleepy, "says Dr. Esparaz.
So, in theory, wearing blue-light-blocking glasses should help people who watch movies in bed or read from a tablet at night avoid sleeplessness. A 2021 review study from the University of Oklahoma that looked at 24 previous studies found that people affected by sleep disorders, jet lag and shift work fell asleep faster after using these glasses.
As for eye strain, a 2021 Australian study showed that those wearing the glasses did not experience less eye strain than those using clear glasses. And a 2018 review study, also by Australian researchers, found insufficient evidence that they prevent certain eye diseases.
"These glasses aren't going to be harmful, " says Dr. Esparaz, But, she adds, a lack of standardization in the industry means there's no way to know if one pair is better than another. A more reliable solution: Turn on the blue-light-filtering function on your devices and limit screen time before bed. To help with eye strain, Dr. Esparaz suggests taking breaks and using lubricating eye drops.
