Blue Light Exposure Calculator

Current evidence does not support that claim. The American Academy of Ophthalmology states there is no scientific evidence that the kind or amount of blue light from computer and phone screens is damaging to the eyes, and does not recommend special eyewear for computer use on that basis. The Daily Exposure Score here is a screen-habit planning metric, not a measure of eye damage risk.

The controlled research says largely no. Multiple studies, including a 2023 Cochrane Database review, found that blue-light-filtering glasses do not reduce the eyestrain symptoms people experience after computer use. What this calculator's Blue Light Filter Level input changes is the exposure score itself, not a proven reduction in strain symptoms -- those come mainly from reduced blinking and sustained near focus.

Staring at a screen reduces how often you blink, which dries and irritates the eyes, and sustained close-range focus fatigues the eye's focusing muscles over hours of use. Both mechanisms are independent of the blue light wavelength itself, which is why taking regular breaks -- the 20-20-20 rule this calculator's break recommendation is based on -- addresses the strain more directly than filtering blue light does.

Yes, for sleep specifically: evening blue light exposure can suppress melatonin and delay sleep onset, which is why avoiding screens for two to three hours before bed is a commonly recommended practice. That circadian effect is a separate mechanism from eye damage or daytime eye strain, and it's the one area of blue light research with genuinely stronger supporting evidence.

It recommends roughly three breaks per hour of screen time, which lines up with the American Optometric Association's 20-20-20 rule: every 20 minutes, look at something 20 feet away for about 20 seconds. That cadence is a genuinely evidence-informed recommendation for reducing digital eye strain symptoms, independent of whatever blue light filtering setting you use.