My high school teacher of a class called Brain Studies told us that certain light is overall “better” for you. It had something to do with emulating sunlight, and being whiter (less yellow). These bulbs are also significantly more expensive.
Anyone have any idea what he was talking about? This was 10 years ago and I can’t track the guy down.
Aye, your old Brain Studies teacher was right. We’re best at coping with light that’s as close in spectrum and intensity as sunlight.
Normal incandescent bulbs give a bit of a yellow hue, and though my socks may look a matched pair when I put them on in my bulb-lit bedroom, a foray out into the sunlight invariably reveals one of them to be black, the other dark blue. Incandescent bulbs don’t flicker like fluorescents, but they’re still not very good for colour rendering.
Fluorescents are bloody awful, and even the ones that claim to be “daylight” spectrum are no subsititute for an incandescent bulb. If you look at the spectral chart of a fluorescent, you can see it’s made from a limited series of big spikes, rather than a nice smooth distribution like sunlight. This means that the colour rendering usefulness of fluorescents is very limited, and your brain has to do extra work in processing image information because certain colours are essentially missing.
I like halogen incandescent bulbs. They give a lovely white light, and you can read and do close work with the minimum of eyestrain. A little expensive, but worth it. You don’t need to fit halogens all round the house - I just have them on my desk, in my workshop, and in the kitchen. I use low-energy fluorescents in hallways, where the quality of light isn’t too important, and normal incandescent bulbs everywhere else.
For a very good overview of the spectral outputs of different types of lamp, mouse-click you way to here.
Fair enough, but…
The spectrum of the raw sunlight itself? The spectrum of sunlight at midday on a clear summer’s day, which has a distinctly blue weight? Or at sunrise or sunset, where it’s redder than an incandescent? Our eyes have evolved to accomodate a fairly wide range of white light compositions.
I’ll buy that the flicker on fluorescents may cause some problems, and there may be issues with colour temperature and SAD for susceptible people. But I don’t buy that standard incandescents have health deficiencies because they have a lower colour temperature than daylight.
Disclaimer: Though I first read about this school of thought in 1986 (Mother Earth magaqine, Jan/Feb 1986,) and research has been done since then, it is still controversial.
John Ott has long been a proponent of the idea that full-spectrum light is better for the health of people and animals than standard incandescent and fluorescent light. The sun’s light is a particular mix of many colors. We see this mix as white. The fluorescent tube, usually available in “cool white” or “warm white” has a narrower mix of colors than the sun. So does an incandescent light bulb. Ott believes that the frequencies left out of our most common bulbs are vital to our well-being.
He sells the Ott Light®, which produces a mix of colors very close to sunlight. It’s not cheap. You can also buy fluorescent tubes that mimic the color of “sunlight at noon.” Check at a lighting store or electrical supply place. One brand calls it “Design 50.” It’s not a standard item you can find at KMart.
Another part of the picture is light therapy for Seasonal Affective Disorder (depression, lethargy and overeating when the days get shorter.) One treatment for SAD is exposure to bright full-spectrum light before dawn. The idea is to trick the primitive hypothalmus in the brain into acting like it’s springtime. This is another area that’s fraught with controversy.
In my drafting days I remember seeing special desk lamps that were made from a single doughnut-shaped fluorescent lamp with an incandescent bulb filling the doughnut hole. One of the guys told me that the mix gives a better light for drawing than either alone.
Nothing more to add, though.
Depends upon the application. For colour rendering, noon on a clear day. For a cosy warm atmosphere, sunset…
There’s an interesting phenomenon that can be seen for a few minutes near sunset. A lot of flowers have ultra-violet markings (some pollinating insects can see UV), and some plant species like Tagetes (marigold) or globe artichoke will produce flowers that glow with some degree of praternatural incandescence at this time of day. This is because the percentage of UV in daylight at sunset is quite high, even though the overall light levels are low - handy also for cyclists with fluorescent clothing.
I wasn’t suggesting normal incandescent bulbs are nasty - they’ll have a colour weighting towards yellow*, but it’s a nice gentle slope. Still makes me leave the house with odd socks though. But you can think of the spectrum in a fluorescent as a series of spikes in the red-ish, green-ish and blue-ish areas of the spectrum, giving an overall white-ish effect. But white it ain’t. It’s white-ish, made from 3 almost monochromatic colour spikes.
As for the flickering - it’s illegal in a UK commercial workshop to operate machinery with exposed moving parts (drill pillars, lathes, grinding wheels etc) solely under fluorescent lights, as the strobing can make the turning machine part seem slow or stationary. If the workshop is lit with fluorescents, then incandescent lights must be provided for the machines.
minor7flat5 - a mixture of blue-weighted “daylight” fluorescent and a normal, yellower incandescent will indeed give a result greater than the sum of the parts. Obtaining a decent spectral balance from artificial lighting is not easy, and often involves a mix of lamp types. Or something exotic and expensive, like a xenon short-arc lamp.
*For some reason, I once fitted a red fireglow lightbulb in my kitchen, giving the effect of a submarine on alert. The brain adjusts slightly to colour weighted light, and so the normally red glow of the electric hobs looked pure white under red light.
[continuing tangent]One fine day while serving on the Nimitz I went to the ship’s store and bought a pack of Good’n’Plenty. I took it to my berthing compartment, where we had red light on after hours. I sat there for a few minutes looking in amazement at my handful of candy: to my eyes it looked like I had opened a box full of white Good’n’Plenty – the pink ones were totally indistinguishable from the white ones.[/continuing tangent]