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Comment by dymk | Hacker News Reader

Sure. Perhaps there's something intrinsically different about moonlight - humans don't have their circadian rhythms disrupted by it, like they do with screens and artificial lights.

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Judging from how hard it can be to sleep during a full moon while camping, I'd say the reason humans aren't generally affected by it is because they sleep underneath opaque shelters that block direct light.

This is something I've wondered about. People keep talking about how it's blue light that keeps you awake, but moonlight is pretty bluish. Why would humans have evolved to have that as the don't sleep wavelength?

Moonlight is white, just like how the sun is white. The moon = blue, sun = yellow connotations are mostly cultural.

Just looked it up. Apparently it's due to the Purkinje Effect, i.e. "The tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the color spectrum at low illumination levels."

I just googled it and apparently moonlight is actually redder (or yellower if you prefer) than sunlight.

Here is a thread with a graph of the spectrum: https://physics.stackexchange.com/questions/244922/why-does-...

You need to be out in open and a very dark place, and with very clear skies, to really notice how bright the moonlight can be - in cities it's just not noticeable. Honestly it never affected my sleep since I was usually dead tired from whole day of hiking and I'm not very sensitive to lights anyways, but I remember on more than one occasion that some people in my group complained not being able to fall asleep or about sleeping bad in semi-transparent tents because of super-bright full Moon.

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