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Comment by ssnistfajen | Hacker News Reader

"bright blue screens until minutes before we think we can sleep" is hardly the case anymore, at least for the majority of those who actually spend that much time. Many desktop OS and mobile OS shipped in the past 3-4 years have built-in night light options that reduce blue hues in the display, for the exact purpose of mitigating impacts of screen usage to sleep.

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Agreed. Was mostly referring to both the artificial light(of any kind) and the distractions on those devices are awful for sleep routine.

I heard those mitigating measures don't do diddly.

I heard that blue light did not do diddly.

Yup. Blue light was/is a recent fad "cure" for sleep issues. The impacts are negligible outside test centers. I have a red-light setting on my phone for 10pm. In practice it is nothing more than a silent alarm that tells me to stop watching youtube.

It feels to me like humans need darkness more than other animals to sleep. I'm curious if this another excuse rather than a real issue.

I suspect darkness works, but only because it mitigates circadian rhythm issues somewhere else.

I fall asleep easier with an eye mask on (and sometimes can't without it), but also feel like I dream more without it, and no dream sleep isn't as mentally refreshing.

I do have some sleep stage measuring gadgets to actually test this, but sleeping with an EEG headband on isn't the most comfortable thing.

You clearly haven't sat in front of bright blue light when you were feeling sleepy. I have a SAD light, and it's about as good as a coffee at waking me up.

It’s the brightness though, not the blueness, apparently.

There are various studies in which they measure the amount of melatonin in subjects' saliva, after exposing them to different wavelengths of light at the same ... well, in this case it's energy rather than lux: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.96...

> Two long wavelengths, 595 nm (amber) and 660 nm (red) and three shorter wavelengths, 470 nm (blue), 497 nm (blue/green), and 525 nm (green) were compared with a no-light control condition. Light was administered via a portable light source comprising two light-emitting diodes per eye, with the irradiance of each diode set at 65 µW/cm 2. [...] Half-hourly saliva samples were collected on the evening prior to the first light pulse and the evening following the second light pulse. The time of melatonin onset was calculated for each night and the difference was calculated as a measure of phase advance. The shorter wavelengths of 470, 495 and 525 nm showed the greatest melatonin onset advances ranging from approximately 40–65 min while the longer wavelengths produced no significant phase advance.

Looking at a second source for lux at different wavelengths... https://www.circadiansleepdisorders.org/info/lux.php

It says light sensitivity peaks at 555 nm, and the graph looks mostly symmetrical (though the red side is slightly higher than the mirrored blue side). If it were all about perceived brightness, then I think we'd expect amber light to have a stronger effect than blue-green or blue, but that was not observed.

The 555 is the peek of the cells that provide vision.

The circadian sensor is separate from vision, it receives light that comes from top, its range goes beyond vision range into ultraviolet, its sensitivity goes up with the light frequency.

The recommendation to go for a walk outside in the morning to fix the circadian rythm is basically to get ultraviolet coming from the top to your eyes, as that is most effective. In the evening any required lighting should be dim, red and coming from bottom.

Blue light screen filters do help somewhat but the sum of the remaining lower bands still has the potentiall to mess up the circadian.

source: Andrew Huberman podcasts on sleep

My experience is that they make a big difference, but you have to set them to be quite strong in order for them to do so. So much so that for example the built in feature on mac/ios isn't strong enough even at the maximum configurable strength! However, 3rd party apps like f.lux on mac or twilight on android can set the redness much stronger at which point it really does make a difference.

If people like redshifting, that's all that matters. Quite a lot of people like it, which is why implementations of this feature have proliferated. What's the point in moaning about the lack of scientific backing? Are you trying to convince people to stop liking a thing they like? For what purpose? It's not as though there is any harm in the feature.

No one I work with uses this in the office. I am the only one and they complain that my screen "hurts their eyes" because of its orange hue.

I would not be so quick to dismiss the effects of staring into light bulbs for 8-12 hours a day.

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