Hi, I read recently in New Scientist that full-spectrum light seems to enhance learning, alertness, and retention.
I’ve been feeling almost narcoleptic lately (seriously. I fall asleep at the drop of a hat) so I want to get some full-spectrum bulbs.
My question is, a lot of the bulbs at Amazon look like they’re just coated with blue plastic or something. What exactly does it take to generate real “full-spectrum” light? What is the difference in constituents between an old incandescent bulb, one of the new flourescent ones, and the sun? Is there an actual scientific standard to which full-spectrum bulbs are held? How close can one get to approximating all the bandwidth of the sun’s light?
No fluorescent or LED light source is going to be a very good full-spectrum emitter. Lamps using phosphors inherently emit in discrete lines. So, the best full-spectrum light source would be a high-temperature incandescent or halogen lamp.
Frankly, I think the benefits of full-spectrum light is a lot of hooey, but that’s just my opinion.
Okay, let me make sure I understand: “lamps using phosphors” would be the coating on the inside of the bulbs? Or is the phosphor in the filament?
So, the difference would be that sunlight is emitted in every direction; and phosphor lamps emit in a narrow beam, not coherent, but discrete?
Forgive me, this is one of the gaps in my knowledge, but why then is it different? Does the discrete beam only encompass a portion of the bandwidth that the broadbeam incorporates? (I guess I was thinking it would be more like a piece of a hologram – a smallscale version of the whole.)
Heated filaments emit light by “Thermal radiation” - the light is a continuous spectrum, and follows a curve proportional to the temperature of the filament.
Fluorescent and LED lamps emit light in quite a different fashion. They use UV light to stimulate phosphors which then fluoresce, and emit visible light. This emission occurs at discrete wavelengths. A careful mix of phosphors can simulate sunlight passably, but it really is just a lot of discrete wavelengths of the correct intensity to fool the eye.
Oh! I see now. So, with a good phosphor mix, you might get “green-yellow” and “cornflower blue,” but unless you got “periwinkle,” “thistle,” and all the others, you ain’t got a box of Crayolas.
Another one of my incomprehensible analogies. Thanks, **beowulff. ** I think I’ll skip the purchase then, because man that Amazon S&H hurts!
The theory of the health benefits of full spectrum light is precisely that while your eye considers green-yellow + cornflower to look white enough, proper vitamin Q metabolism or whatever really demands periwinkle too.
I think the theory is bunk at the biological level even though it does start from legit physics. But that’s IMO.
Well, the article I read wasn’t from a health-benefits angle; it spoke of a year-long controlled study at the University Medical Center in Hamburg. Though the sample size sounded somewhat small to me – 166 students – they found that very significant improvements were seen in cognition along with a dramatic decrease in errors when full-spectrum lighting was employed.
(Perhaps I should have put “full spectrum” in quotes, because they weren’t talking about sunlight but manmade lighting.)
I looked carefully at New Scientist’s website for a cite to give here, with the magazine in hand; but I guess their online content differs from the dead tree version.
Let me ask one more question: Does putting radiant light from a bulb through a blue filter (like a blue coating on the bulb) result in the same thing as light actually emitted in the blue wavelength? Seems like it couldn’t, because the coating couldn’t be every shade of blue simultaneously.
I own a photo lab and we installed full spectrum lights to facilitate color checking pictures. My whole staff commented on how they felt ‘better’ after a few weeks. It’s a subtle, but definitely real effect. Since the florescent bulbs are lees than $10; I’d say it’s worth giving a shot.
My father has that. That is a very apt suggestion. I have no insurance, but perhaps I can find a way. Thanks for the good advice.
And chacoguy, thank you too. They are actually even cheaper on Amazon. However, I would rather go with a known winner – can you PM me with the manufacturer’s name, if it’s not too much of a hassle? Thanks a lot!
This isn’t true, strictly speakinhg. Although the old fluorescent lights did have a lot of discrete spectra, many phosphors emit broad-band radiatioon. A case in point is the current crop of “white light” LEDs. The base wavelength, emitted by the LED itself, is blue, but it’s used to excite a phosphor packaged with the LED, which emits a very broad band of longer wavelength light. If you look at this through a spectroscope, you can’t make out individual sharp lines. Some of the LED-phosphor combinations are excellent, looking just like ordinary white light. (Unfortunately, most of the ones you buy at electronics stores still aren’t, and have a distinct blue cast to them.)
The key is the 5500k color temperature. Who makes them and where you buy them is less of an issue. Again, this is not some “Solve all your problems” thing. Star with you kitchen and where you spend most of your time. Buy them for you space at work. See if it affects how you feel. Try it during the Winter. If it totally doesn’t do jack, you’re out, maybe $50.
It is important to realise that there is a huge difference between a simple light that claims 5500k colour temperature and a D55 or D65 daylight source. Domestic light sources essentially provide their colour temperature by illuminating a pure white surface and measuring the colour the eye sees, and relating that to the colour seen when the same surface is illuminated by a real black body source. A D65 source is a very high quality approximation across the visual spectrum to the light we see from the sun at the earth’s surface, and also includes the contribution from the blue sky. It is defined at 2nm intervals. A domestic light could achieve 5500k equivalent light with only three emission lines. Colour fidelity when illuminating coloured objects can be dire.
A real D65 light source is insanely expensive and they are only made for professional colour and light scientists. Lights marketed as full-spectrum are typically far from this, and indeed some expensive full-spectrum lights are indistinguishable from cheap tri-phosphor florescent lamps. There is some serious psuedo-science bandied about with these lights too. I have seen some claims that the UV component is critical. Which both stupid and dangerous.
In terms of value for mood and the like, there is evidence that very high intensity white light can help. This is a different issue.
You know what? I’m embarrassed to admit this, but the “article” I read was an advertisement, so designed as to be virtually indistinguishable from the real articles in the magazine. That doesn’t necessarily negate what it said, but it puts it in – a different light. Heh.
FWIW – I have been using Ott Lite fluorescents in my computer room (where I spend a lot of time) for quite a few years. I don’t find the actual Ott-Lite brand lamps to be very well designed, but I put the bulbs / tubes into other lamps.
Just about everyone who comes into this room makes some sort of comment regarding the lighting … though sometimes just to mention how orange the incandescent lamp looks. It really does make a big difference in the perception of colors, seems to reduce eyestrain, and is great for reading.
It’s been several years since I did the research so I don’t really recall now how I decided on the Ott-lite brand when I was working on the ergonomics of my workspace but I do recall reading that Germany had banned the use of cool-white fluorescent lights and that was a big factor in my decision to try full spectrum lighting.
I do recall that it was difficult to determine what was woo, what was advertising, and what was real … but I have continued to buy replacement bulbs even though they are more expensive than regular lights. In general, I don’t like fluorescent lights but these are ‘different’.