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Comment by JimboOmega | Hacker News Reader

I don't quite understand. Blue light - any blue light - causes blindness? So we shouldn't look at the sky even?

I've never heard blue being a danger other than its effect on the biological clock, so that seems like a pretty bold claim. Ultraviolet, sure...

Though buried in there is something about immune system and vitamin E levels...

I really find it hard to believe that blue light exposure is automatically bad. We have receptors for that specific purpose. Wearing blue light filtering sunglasses all the time as the article suggestions seems a bit ridiculous. Why give up one color entirely?

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The first thing to realize about any scientific paper is that it's wrong. To a very good approximation all scientific papers are wrong, until the results are replicated a couple of dozen times and failed to be replicated a few times this could well be an artifact of the methods they used.

Never make life changed based on the results of one single study.

It says that your body's normal antioxidants prevent damage. This is only a problem for people who have low levels of alpha tocopherol, e.g. from malnourishment or aging.

We have chemical receptors on our tongue and in our nose for poisons. We have neurons that detect pain. Just because we can sense it doesn't mean it's not harmful.

But those receptors signal something unpleasant - a terrible taste, pain. Looking at blue doesn't cause pain or unpleasantness.

I'd guess that the negative effects of blue light over a lifetime might only have become noticeable in modern times, with better vision correction and treatment for conditions like glaucoma and cataracts. If so, there probably hasn't been significant evolutionary pressure to dislike viewing blue light. Also, half of outdoors is blue half the time, so instinctual blue-avoidance would probably hurt survival.

But it is perhaps misleading to concentrate on things that are exclusively blue... The real problem is light containing the relevant range of frequencies, which includes many non-blue colors, due to the relative presence of other frequencies. For example, your eyes would probably absorb much fewer relevant photons when staring at an empty patch of sky than when staring at the sun, even though the sun is not considered blue. And looking at the sun does cause unpleasantness.

On the contrary in fact, I find gazing at the blue sky to be calming and enjoyable, and find it promotes diffuse thinking, which can greatly speed up problem solving.

It's not about merely seeing something blue, like the sky, in a generally warm temperature ambient light. It's about blue color from screens.

Some people like the smell of ozone.

Ozone doesn't have a smell. What you actually smell is your nose burning. Ozone is a very aggressive oxidizer.

Looking directly at the sun is also a super bad idea.

> Ozone doesn't have a smell. What you actually smell is your nose burning. Ozone is a very aggressive oxidizer.

Wait, what? Do you have a source for this?

> Ozone doesn't have a smell.

This does not sound right. This is what I see on Wikipedia which is also exactly what I was taught in high school:

> It is a pale blue gas with a distinctively pungent smell.

Source: https://en.wikipedia.org/wiki/Ozone

I don't think your argument holds. Case in point: it is possible to make poison tasty.

Try gazing unprotected at a nearby arc welder flash.

Just speculating here, but I‘d say since eyes have evolved to also look at the sky, I’d say no. Shining a laser on cells is different from sunlight in various ways. First, laser light waves are coherent (perfectly overlapping), so their effect might amplify A LOT. The dosage (J/cm) used by the researchers also might be 100x as high as the sun‘s, for all we know. Then, there’s the thing that sunlight is a mixture of a very broad range of frequencies, from far infrared (and below, microwaves etc) up to ultraviolet (and beyond, eg X-rays, which luckily don’t arrive at the earth surface in huge doses). Again, just speculating, but near infrared has been found to have a beneficial effect on retinal diseases, so maybe it compensates for the problems blue light creates.

"since eyes have evolved to also look at the sky"

On the other hand the Inuit had to invent snow goggles to prevent blindness caused by the bright sun reflected off the white snow-covered terrain. Like, actual eye damage blindness. That's been attributed to UV but perhaps blue wavelengths play a role as well.

As others mentioned:

When you look at the sky during a bright day your pupils are narrow and let little portion of the light through. When you look at blue light in the dark - they are dilated and let more light through.

>I really find it hard to believe that blue light exposure is automatically bad.

Few things are "automatically" bad. Over time though, effects are cummulative, and there are also breaking points for lots of bad stuff.

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