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Comment by achille | Hacker News Reader

I'm surprised behind the huge push behind a "soft yellow" colored bulb. The articles makes a claim that humans prefer the yellow/orange glow due to prevalence of fire as lighting.

But I don't see a single mention of the color termperature of pure sunshine, which is much, much closer to pure white (5500K).

Flourescent bulbs that glow at 5500K are considered "pure white" [0] and seem to be demonized in the article as too harsh.

I think this is a case of old folks that grew up under incandescents and prefer them purely because they grew up with it. As Steve Jobs has mentioned [1] (about keyboards), we just need to wait for them to die out eventually.

[0] http://www.pse.com/savingsandenergycenter/ForHomes/Publishin...

[1] http://orangejuiceliberationfront.com/theyll-die-out-eventua...

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I like the sun just fine -- when I'm outside during the day. However, the color of light is important to the human sleep cycle. If you fill your house with sun (blue) colored lights, you're going to shift your melatonin production later and may have a hard time going to sleep. Humans have evolved with blue light during the day and yellow light at night for quite some time, so I think it's more than just a nostalgic preference.

From "Effect of Illuminance and Color Temperature on Lowering of Physiological Activity":

"...we surmise that the effect of color temperature is greater than that of illuminance in an ordinary residential bedroom or similar environment where a lowering of physiological activity is desirable, and we therefore find the use of low color temperature illumination more important than the reduction of illuminance. Subjective drowsiness results also indicate that reduction of illuminance without reduction of color temperature should be avoided."

http://www.jstage.jst.go.jp/article/ahs/18/4/18_117/_article...

This is why I use Flux on my Mac: http://stereopsis.com/flux/

My (little) kids make a big fuss if I try to put in any "sunlight" spectrum bulb of any sort. They complain that it is bluish, cold, and "yucky." Their favorite is any intense halogen (not the blue headlights, but indoor yellow-white), which seems to me to have a color temp of 2700-3300 or so. They also like ordinary incandescent bulbs.

Natural sunlight seems yellowish-white to me when you are in the warm sun, and only feels bluish-white when you are in a cold shadow (in the snow or beside a lake). Being in shadow on sand or dirt doesn't seem bluish because of the reflected light. When sunlight is streaming through the windows of the house but not landing on me, so I'm in the shade, it seems yellowish-white without a trace of blue. We have various "earth tones" on the floors and walls, not blue, so that influences the room light. A sunlight spectrum fluorescent seems bluish, so it doesn't seem like sunlight.

It appears that we want to feel that we are in a warm place, and the sunlight spectrum is making us think we're in a cold shadow. I also suspect that the mismatch between "sunlight spectrum" and real sun has something to do with reflections. A modified sunlight spectrum bulb could add the effect of earth tone reflections into the bulb color.

I tried to do the same thing for myself with some sunlight bulbs in my bedroom and I couldn't stand it.

I'm with you. I hope that we aren't forever doomed to a world of yellow light by the preferences of past generations. I'd love to buy some dimmable cold-cathode fluorescent lights, but I can only find them in ~2700K.

I don't know if it's been experimentally verified, but to my perception, color temperature is a lot more complex than blue for day, yellow for night. I find that as light levels approach blackness, I prefer higher color temperatures once again (possibly mimicking moonlight). I have many more ideas for optimizing lighting and color temperature throughout the day, which I hope to apply in the next phase of my current startup.

Moonlight is actually 4100 K, colder than incandescent, but warmer than regular daylight.

I think the reason fluorescent lightning looks bad is not the color temperature, it's the narrow spectrum of emitted light.

Fluorescent doesn't actually have a narrow spectrum. What it has is very strong peaks by certain lines.

i.e. most of the light is UV, which is converted to other colors by phosphors - in precisely the same method LED uses. If it stopped there it would be great.

But it also makes visible light in narrow peaks, and this messes with the color, so they compensate by adjusting the phosphors for the complementary color, but that hurts the color rendering.

And the flicker.

Modern "electronic" fluorescent ballasts don't flicker, at least when not broken. (They use a frequency that is high enough that the phosphors' glow hasn't stopped before the cycle is over). The old "magnetic" ones did, but those really ought not be used anymore. They're less efficient and often flicker and hum.

Bulbs at the end of their life can flicker, but those of course should be replaced.

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