Red Light And Circadian Cycle

J

j.

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I read the interesting claim that red lights are used for night illumination because they are supposed to be safer in terms of interference on the circadian cycle.

Is there any truth to that? What are some interesting implications?

They give a bit more explanation:

The mammalian eye senses the light by the conventional rode and cone cells. However, a third light-sensing cell type has been recently identified. This third light-sensor is based on melanopsin-positive cells. While rod and cone cells respond best to white, full spectrum light, melanopsin cells only respond to a specific bandwidth of blue light, in the range of 446-477 nanometers. These cells connect and regulate brain centers responsible for circadian rhythms. Therefore, during the night, blue-light exposure might interfere with circadian rhytms facilitating the onset of depression and other metabolic derangements associated with circadian cycle see another SE question. White light contains also blue light, while red light does not. This is apparently the rationale to claim that red light is less harmful. However, no clinical evidence is available to my knowledge, and the threshold of blue light required to stimulate melanopsin receptors is probably over the common night illumination.
 

fyo

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short wavelength light at around 460 nm is most effective in acutely suppressing human melatonin levels... People given dark, then 2 hours of light exposure, then darkness. "There was no significant difference in sleepiness between the 550-nm light exposure and the no-light condition"... We have obtained very similar results as Brainard et al. who reported approximately 60% suppression of melatonin after 2 h of light at 460 nm. http://jcem.endojournals.org/cgi/content/full/90/3/1311

It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue) light and is quite insensitive to long-wavelength (red) light. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2744917

goggles with selective exclusion of all wavelengths less than 530 nm... All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. http://jcem.endojournals.org/cgi/content/full/90/5/2755

either blue-blocking (amber) or yellow-tinted (blocking ultraviolet only) safety glasses for 3 h prior to sleep... the amber lens group experienced significant improvement in sleep quality relative to the control group and positive affect. Mood also improved significantly relative to controls. http://www.ncbi.nlm.nih.gov/pubmed/20030543
 
OP
J

j.

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Great info. It seems to make sense, but I wonder what Peat thinks of it.
 

Peater

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This forum could not have a worse colour scheme for browsing at night then :lol: (22:00 here in UK)
 

charlie

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Redshift or f.lux is helpful. :)
 

Mittir

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Peater said:
Charlie said:
Redshift or f.lux is helpful. :)

I use f.lux, but it doesn't turn blue to red (sadly)

Are you using "lighting at night" setting at Ember? That is 1200K
color temperature. I feel sleepy within half an hour on this setting.
I usually use 1900k setting.
 

Peater

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Sorry I don't know what that is, a Google search just bought up some iPhone app results
 

Mittir

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Peater said:
Sorry I don't know what that is, a Google search just bought up some iPhone app results

If you open f.lux, there is a bar next to "Done". If you click that bar you will see
"Setting at night". Then choose Ember or other setting.
 

jyb

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Mittir said:
If you open f.lux, there is a bar next to "Done". If you click that bar you will see
"Setting at night". Then choose Ember or other setting.

Ah, that's helpful. Stupid of me, didn't realize the default night settings is a full incandescent color!
 

paper_clips43

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Thanks everyone for posting about F Lux, I just download it :)
Can we just use dark room mode all the time? It seems to be much easier on my eyes.
 
OP
J

j.

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For what it's worth, I'm more comfortable using a real physical filter combined with flux at 3000K, than reducing Flux to 2300K or less. I don't know how to measure it but I believe the physical filter combined with flux at 3000K has a lower color temperature (i.e., is more red) than flux alone at 2700K.
 

Peater

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Mittir said:
Peater said:
Sorry I don't know what that is, a Google search just bought up some iPhone app results

If you open f.lux, there is a bar next to "Done". If you click that bar you will see
"Setting at night". Then choose Ember or other setting.

Done! Thanks
 
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