Approximate wavelengths, in nanometers (nm):
[Strongly] suggested pre-reading: Artificial light and circadian rhythms: blocking the blues and The Hot Blue-Blocker Experiment
Study 1 tested the effects of different wavelengths of light exposure (compared to total darkness) from midnight til 2 AM on melatonin suppression on night 1 and melatonin onset on night 2 (Wright and Lack, 2001). Note: there was no light on night 2.
On night 1, they found that 470 (blue), 497 (blue/green), and even 525 (green) suppressed melatonin, ranging from 65 to 81%.
However, remarkably, on night 2 those same wavelengths had a carry-over effect, delaying melatonin onset by 27 to 36 minutes!
This is why lens color of your blue blockers matters. Orange lenses block blue, although blue/green and even green can still have a detrimental impact. Redder lenses more effectively block in the green range.
If you get up to pee or whatever in the middle of the night, it might be prudent to rock your blue-blockers and/or have a lamp with a red bulb.
The following graphs show you how much light is blocked by different lenses – remember, we want as little transmission up to around 525 nm (according to study 1 [above] and study 2 [below]).
However, for a quick and dirty test you can do at home, the people at Spectra479 put this together:
Normal gray-lensed Ray-Bans block about 85% of all light. Cool for blocking UV, but you’re still getting about ~15% of blue and green light. That’s too much.
Spectra479s block 99.8% of 450-510nm, which fully encompasses blue to blue-green.
Carbonshades block 99.8% of 400-570 nm, which fully encompasses blue to green, so the largest range of protection according to study 1 (above) and study 2 (below).
For more steps on how to strengthen your circadian rhythms, the potential importance (and relevance) of blocking BLUE/GREEN, and a discussion of the science… head over to Patreon! Three bucks a month gets you access to the rest of this one and ALL other articles! Plus more options under the “Reward” section. Ad-free 🙂
Also many more interesting tidbits and some advice, like who might need to upgrade their blue-blockers.