alt Hacker NewsI found the basic premise of this blog post to be incredibly flawed. The author seems very sure of himself that blue light filters don't work, but making arguments related to cell types and emissions spectra and circadian rhythms is not the way to make a conclusive argument in a topic like this. Science is littered with recommendations about things that "plausibly" made sense, but that turned out to be flawed or just absolutely wrong when actually put to a real, scientific test. One example most people are familiar with: the recommendation against eating eggs in the 90s was based on the fact that eggs have a lot of cholesterol, and we knew high LDL levels in blood were associated with a greater risk of vascular and heart problems. So, "logically", it seemed that limiting dietary cholesterol would reduce heart disease. Except when scientists actually tested those recommendations, they turned out to be largely wrong - when you eat a lot of cholesterol, for most people their body's natural production of cholesterol goes down, so unless you're in the small subset of people who are particularly sensitive to dietary cholesterol, eating eggs is fine.
Making recommendations based solely on a theoretical mechanism of action is bad science. The only way to actually test this is with a study that looks at different types of light restriction and its effect on sleep. Obviously it's kind of impossible to do a blinded study for blue light filters, but you could get close by testing various permutations of light changes (e.g. total luminescence, eliminating only very specific wavelengths, etc.)
As another commenter said, it may be a placebo effect, but if it is, who cares? All I care about is that I get a better night sleep, and as someone (unusual among programmers I know) who really doesn't like dark mode, a screen reddener greatly helps me at bedtime.
Replies
His argument seems to be that the night modes don't remove much blue. My initial assumption was that it was about physical filters. Yellow or amber 99%+ safety lenses are a thing and several of my coworkers wear them. Looking through them at those painfully bright blue leds makes them appear to be off. Yes everything looks strange, but they work. Likewise a different coworker manually removes all blue in the monitor settings themselves independent of the brightness setting. That also works. The author's assertion should be qualified amd narrowed a bit.
But you could make your same argument for the pro blue light filter side.
Did you read the article? He points out “It’s possible that Night Shift does something, but the biggest study I could find of Night Shift mode (still a pretty small study) found little effect on sleep, so if there’s an effect, it must be tiny.” He links the exact type of observational study you asked for
Regardless the maximum possible effect will be constrained by the biology of the cells responsible for responding to blue light. Maybe knowledge of the biology is incomplete or flawed but to not use it to inform what’s possible seems foolish.
So what if it’s a placebo effect? Well some people are spending money and time investing in blue light filtering glasses and other solutions. It’s potentially snake oil and it could keep them from pursuing better solutions that would actually help them sleep
Blue light blockers are a scam that was created when some circadian rhythm research went viral (in a highly misrepresented way) online a few years ago. It's a stunt to make some quick cash from unwitting buyers.