The claim: blue light causes eye strain
Before comparing solutions, it's worth establishing what problem we're actually solving. The blue light hypothesis — that blue-wavelength light from screens causes eye strain and retinal damage — became popular around 2010 and spawned an entire glasses industry. In 2021, the American Academy of Ophthalmology released a position statement: there is insufficient evidence that blue light from screens causes eye damage or is a primary driver of digital eye strain.
Where blue light does have strong evidence: sleep disruption. Blue wavelengths suppress melatonin production more than any other wavelength, delaying sleep onset and reducing sleep quality. This is a real and meaningful problem — but it's a sleep problem, not a direct eye damage problem.
Do blue light glasses actually work?
A 2021 Cochrane review — one of the most rigorous summaries of medical evidence available — looked at all available trials of blue light glasses and concluded there was low-quality evidence of any reduction in eye strain, and no clear evidence of protection from eye disease. A 2023 randomised trial found no meaningful difference in eye strain or sleep quality between blue light glasses wearers and a control group.
That said: some people report subjective improvement. Whether this is a real optical effect, a placebo effect, or the result of the glasses prompting better screen habits (taking breaks, being more aware of screen time) is unclear from existing research.
Does night mode actually work?
Night mode (Night Shift on iOS/macOS, Night Light on Windows/Android) shifts the display colour towards warmer tones in the evening by reducing blue light output. The evidence for sleep benefit is mixed but more positive than for glasses: several studies have shown that warm-toned screen settings in the evening reduce the melatonin-suppressing effect of screen use, though the magnitude of the effect depends heavily on timing and intensity settings.
For eye strain specifically, night mode has limited daytime benefit — it doesn't address the underlying mechanisms of digital eye strain during normal working hours.
What should you actually do?
Enable night mode on all your devices and set it to activate automatically from early evening (6–7pm). It's free, consistent, and has the best available evidence for the thing blue light most clearly affects: sleep. Use f.lux on your computer if you want more aggressive and customisable warmth.
Blue light glasses are unlikely to be harmful and some people find them helpful — but spend money on them only if you've already addressed the much higher-impact factors: screen distance, break frequency, lighting, and blink rate. These are responsible for the vast majority of digital eye strain, and none of them are solved by glasses.
The thing neither addresses
Neither blue light glasses nor night mode does anything about blink rate — the most significant driver of digital eye strain. During screen use, blink rate falls by up to 70%, causing tear film breakdown and the dryness, burning and irritation most people experience. This is the variable that most directly determines how your eyes feel at the end of the day, and it's addressed by neither solution.