3 ms·

(Post author here, huh, it hit HN...) This is not consistent with the studies I've read. It's a "total lumineous flux in the 460-490nm range" concern. The de

by Syonyk 4y ago

(Post author here, huh, it hit HN...) This is not consistent with the studies I've read. It's a "total lumineous flux in the 460-490nm range" concern. The deep reds, up past 600nm, don't seem to have any impact on melatonin, nor do violets below ~420nm - though they can have other impacts on the retina and such. Bright light will, all other things being equal, be worse than dim light, but "dim blue light" is still really bad for melatonin levels and sleep. Some of the older studies did find an impact up in the greens, but they were for fairly short duration exposures - 30 minutes or so. The impact of the longer wavelengths, over a longer term, seems to be muted by [mechanisms somewhere in the system], leaving the blues with the most impact. You're welcome to trust Huberman, but I'd encourage you to read the papers yourself (I've read dozens and simply picked the most relevant here). There's quite a bit of work on this matter from the past 20-30 years, and they all seem to conclude that "blues matter." Greens and above don't have nearly the same impact, and they don't have the longer term impact. I'll also suggest being careful about conclusions drawn purely from the absorption spectrum of the molecules involved, as the body doesn't seem to react directly to them, but to some skewed version. Unit tests are nice, but end to end tests cover all the details in the process.

ChickenNugger 4y ago
Since you seem super duper into this, you could try what I do on many evenings even just as an experiment. I just strap on a very nice LED headlamp that has a pure red LED that I use for "night mode". That it uses way less power is actually just a side effect of me wanting all the blue lights off at night. I know it's not for everybody, but I find it really relaxing. The trick is to get one that's not a joke lamp from china with a fat markup but a nice headlamp with powerful LEDs. Like this: https://www.blackdiamondequipment.com/en_US/product/spot-400/?colorid=10696 https://www.blackdiamondequipment.com/en_US/product/spot-400... The relevant bit being: "Settings include proximity and distance modes, dimming, strobe, red LED night-vision and lock mode" I also have a couple of 'hurricane' lanterns and I really enjoy the fire-based lighting but even with "clean" kerosene the smell can be unpleasant indoors.
- sundvor 4y ago
  Somewhat likewise I set my Hue lights to red or a dark orange at night; this seems to work well, at least for me.
  - etherael 4y ago
    There's even a home assistant blueprint that is quite nice for matching the external colour temperature for LED lights that support it, it's basically flux for your LED Lights. https://gist.github.com/HarvsG/cc86381dc99169159d6d4cd870c36e46 https://gist.github.com/HarvsG/cc86381dc99169159d6d4cd870c36... This plus dimming plus red lights in the bedroom and flux for devices I have found works pretty well.
    - sundvor 4y ago
      Nice, thanks!
safety1st 4y ago
Ooh the post author! I have a question. When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship? I buy dim bulbs that have a temperature of 2700K for evening applications precisely because of this belief that brightness and color impacts sleep quality, am I right or is it just placebo? It seems to help...
- Waterluvian 4y ago
  I think the temperature is describing, in a way, the dominant wavelength (think the peak of a normal-ish curve on the EM spectrum). A lightbulb that appears less blue will inevitably be emitting less blue. But that’s not to say it isn’t emitting across a broad swath of the spectrum and you’re still getting the wavelengths that are being argued as problematic to sleep. You’d need more data or tools to determine just how much of the “offending” wavelengths are making it into your peepers. Anyways, hopefully a real expert chimes in. :)
- alwayslikethis 4y ago
  Temperature describes a distribution of wavelengths. Higher is bluer, lower is yellower. Both brightness and color matters. If you want to be as safe as possible, buy pure red LEDs for use 1-2 hours before bed and don't expose yourself to any non-red light. The difference is (no pun intended) night and day.
- lightedman 4y ago
  "When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship?" Hi! LED and LASER module design and manufacturing tech here! There is a small correlation with LEDs and luminous flux - the ones with higher green peaks (2700K-~4000K CCT) will have a higher luminous flux at full power as green (~552nm) is where the lumen is weighted and those tend to have more output in that converted color range versus the cool white (which have a little less green and a bit more blue.) This really only applies to phosphor-converted LEDs, RGB combo LEDs are narrow-spectrum in emission, and you can't really describe them by luminous flux, rather photon flux or radiant flux per output channel, as the luminous flux will always be highest from the green LED, no matter what, due to the weighting of the lumen in the green wavelengths.
alwayslikethis 4y ago
Keyword to search is melanopic spectral efficiency.
mohaine 4y ago
This is covered by Huberman. Our night vision is ~3x more sensitive to blue light than red, probably because starlight has more blue. Blue light is ~2.5 worse for keeping us up but would actually be better if turned it way down like the 3x implies we can. At normal levels the 3x gets lost in the exponential to much light we get at night.

by Syonyk 4y ago

ChickenNugger 4y ago

Since you seem super duper into this, you could try what I do on many evenings even just as an experiment. I just strap on a very nice LED headlamp that has a pure red LED that I use for "night mode". That it uses way less power is actually just a side effect of me wanting all the blue lights off at night. I know it's not for everybody, but I find it really relaxing. The trick is to get one that's not a joke lamp from china with a fat markup but a nice headlamp with powerful LEDs. Like this: https://www.blackdiamondequipment.com/en_US/product/spot-400/?colorid=10696 https://www.blackdiamondequipment.com/en_US/product/spot-400... The relevant bit being: "Settings include proximity and distance modes, dimming, strobe, red LED night-vision and lock mode" I also have a couple of 'hurricane' lanterns and I really enjoy the fire-based lighting but even with "clean" kerosene the smell can be unpleasant indoors.

sundvor 4y ago
Somewhat likewise I set my Hue lights to red or a dark orange at night; this seems to work well, at least for me.
- etherael 4y ago
  There's even a home assistant blueprint that is quite nice for matching the external colour temperature for LED lights that support it, it's basically flux for your LED Lights. https://gist.github.com/HarvsG/cc86381dc99169159d6d4cd870c36e46 https://gist.github.com/HarvsG/cc86381dc99169159d6d4cd870c36... This plus dimming plus red lights in the bedroom and flux for devices I have found works pretty well.
  - sundvor 4y ago
    Nice, thanks!

safety1st 4y ago

Ooh the post author! I have a question. When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship? I buy dim bulbs that have a temperature of 2700K for evening applications precisely because of this belief that brightness and color impacts sleep quality, am I right or is it just placebo? It seems to help...

Waterluvian 4y ago
I think the temperature is describing, in a way, the dominant wavelength (think the peak of a normal-ish curve on the EM spectrum). A lightbulb that appears less blue will inevitably be emitting less blue. But that’s not to say it isn’t emitting across a broad swath of the spectrum and you’re still getting the wavelengths that are being argued as problematic to sleep. You’d need more data or tools to determine just how much of the “offending” wavelengths are making it into your peepers. Anyways, hopefully a real expert chimes in. :)
alwayslikethis 4y ago
Temperature describes a distribution of wavelengths. Higher is bluer, lower is yellower. Both brightness and color matters. If you want to be as safe as possible, buy pure red LEDs for use 1-2 hours before bed and don't expose yourself to any non-red light. The difference is (no pun intended) night and day.
lightedman 4y ago
"When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship?" Hi! LED and LASER module design and manufacturing tech here! There is a small correlation with LEDs and luminous flux - the ones with higher green peaks (2700K-~4000K CCT) will have a higher luminous flux at full power as green (~552nm) is where the lumen is weighted and those tend to have more output in that converted color range versus the cool white (which have a little less green and a bit more blue.) This really only applies to phosphor-converted LEDs, RGB combo LEDs are narrow-spectrum in emission, and you can't really describe them by luminous flux, rather photon flux or radiant flux per output channel, as the luminous flux will always be highest from the green LED, no matter what, due to the weighting of the lumen in the green wavelengths.

alwayslikethis 4y ago

Keyword to search is melanopic spectral efficiency.

mohaine 4y ago

This is covered by Huberman. Our night vision is ~3x more sensitive to blue light than red, probably because starlight has more blue. Blue light is ~2.5 worse for keeping us up but would actually be better if turned it way down like the 3x implies we can. At normal levels the 3x gets lost in the exponential to much light we get at night.