Hacker News Reader

Comment by asdf333 | Hacker News Reader

i have seen articles about excessive blue light from led bulbs being bad for your long term eyesight

i wonder if this has similar problems

When David Chapman's "You need more lumens" article came out (which is referenced in the original post), I was on the verge of building a similar setup but at some point read similar concerns on light therapy. Not necessarily effects on circadian rhythm, but retinal damage from staring close to the amount of light.

From https://meaningness.com/metablog/sad-light-lumens : "The clinical studies were done with 10,000 lux provided by a bank of fluorescent tubes in a box that directed most of the light forward. Very roughly, if you are a couple feet from a box like that, 1 lumen produces 1 lux." It'd be interesting to see studies that have these lighting setups but don't involve staring towards them.

The setup that I'm happy enough with: a set of LIFX bulbs in normal light fixtures. They seem to put out more lumens (1100 lumens) than other color-changing led bulbs. If you don't want 'smart' lighting but still want the ability to change color temperature, Philips makes "SceneSwitch" lights (800 lumens) that will cycle color temperature based on turning on/off.

I use a bank of blue LEDs aimed up at a white ceiling for the winter so I spent some time looking into the question. I didn't find anything very definite or concerning.

Note that there is a whole snake oil thing going on with blue light these days. Some of what we see about this stuff might be coming out of that particular industry.

Here's a good selection of research papers https://www.bioshumanlight.com/research/ . It seems like there might be some adverse effect due to the peak at the lower end of the blue spectrum. I'm waiting for the BIOS team to do a consumer product.

You can choose the colour temperature you want. Go for 2500K if you prefer less blue light.

The issue is that all white leds are made by shining a blue led at a yellow phosphor. Rhe blue and yellow balance to whatever temp you pick, but it is still a lot of blue.

It can't be much worse than being under the blue sky.

this comment makes no sense. even assuming these things are equal, no one is just out there staring at the sky for hours on end for the small percentage of time the sky is actually blue.

So when you're at the beach, hiking, or driving on the highway, what are you looking at instead? The blue sky is going to be most of your field of view unless you just stare at the ground.

The blue sky's spectrum doesn't have a giant spike like this:

https://www.benkuhn.net/img/lux/ledspec.png

Yes it does! A giant spike in the blue region is literally what makes the sky blue in the first place. If there weren't such a spike the sky would be white. When you look up at the sky on a typical clear day, you're getting more blue light than almost any one of these indoor setups.

I see your point, I was thinking of daylight in general. But even the blue sky is not quite as spiky:

https://en.wikipedia.org/wiki/Diffuse_sky_radiation#/media/F...

If you look at 460-470 nm where the spike is in the LED spectrum, it's much lower in the blue sky spectrum.

I think the concern is something about the relative amounts of blue light. Not sure what exactly but something like, the human perception of brightness and therefore the self protection of the eye is calibrated for natural light, so the pupil contraction, looking away, etc, is not done correctly in with that unnatural distribution. Anyway I don't know if that's a real effect, but that's what people (should) mean when they're talking about "too much blue".

Blue sky peaks between 500-550nm, this is 100nm more than LEDs, and much more diffuse.

Reply on news.ycombinator.com