3 ms·

I heard that blue light did not do diddly.

sandworm101 5y ago
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.
- Touche 5y ago
  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.
  - Smithalicious 5y ago
    I suspect darkness works, but only because it mitigates circadian rhythm issues somewhere else.
    - astrange 5y ago
      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.
nicoburns 5y ago
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.
- layer8 5y ago
  It’s the brightness though, not the blueness, apparently.
  - waterhouse 5y ago
    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=10.1.1.968.8001&rep=rep1&type=pdf 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 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.
    - mjan22640 5y ago
      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

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.

Touche 5y ago
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.
- Smithalicious 5y ago
  I suspect darkness works, but only because it mitigates circadian rhythm issues somewhere else.
  - astrange 5y ago
    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.

nicoburns 5y ago

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.

layer8 5y ago
It’s the brightness though, not the blueness, apparently.
- waterhouse 5y ago
  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=10.1.1.968.8001&rep=rep1&type=pdf 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 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.
  - mjan22640 5y ago
    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