Debunking Full-Spectrum Lighting Claims

GreenSwirl writes "Full-spectrum light sources often are claimed to promote health, mood and productivity in schools and offices. The Lighting Research Center at Rensselaer Polytechnic Institute in Troy, New York, has published an independent report evaluating full-spectrum light sources. Practically all health claims are debunked and many products are shown to have a less-than-full spectrum. The report was produced as part of the National Lighting Product Information Program, an objective third-party funded by government and utilities."

Comments

Debunking?

[Henry V .009]

Since when does "We don't know" count as a debunking?

Full-spectrum light sources and health. Full-spectrum light sources will not provide better health than most other electric light sources. Recent research has shown that human daily activities are strongly influenced by the solar light/dark cycle. The most notable of these daily, or circadian, cycles is the sleep/wake cycle; but other activities including mental awareness, mood, and perhaps even the effectiveness of the immune system go through regular daily patterns. Light is the most important environmental stimulus for regulating these circadian cycles and synchronizing them to the solar day. Short wavelength (blue) light is particularly effective at regulating the circadian system; long wavelength (red) light is apparently inconsequential to the circadian system. Thus, to maximize efficiency in affecting the circadian system, a light source should not mimic a full spectrum, but instead should maximize only short wavelengths. Even if a full-spectrum light source includes short wavelength light in its spectrum, it will not necessarily ensure proper circadian regulation because, in addition, the proper intensity, timing and duration of the light exposure are all equally important for satisfactory circadian regulation (Rea et. al, 2002).

I would actually be surprised if there were no benefits at all. We already know that sunlight is well correlated to depression levels in a population. And depression is quite well correlated to any number of health factors.

Effects may be just due to bright light

[nixman99]

Here in northern England, the winters get mighty dark. I've found that using a full spectrum light to illuminate a room definitely increases my energy level in the evening. But I've wondered if the effect occurs just because the light is so bright: if feels like it's still afternoon, so my body acts like it.

As a side note, the full spectrum light has the cool effect of giving the house a sort-of radioactive glow 8-)

Well, duh..

[Anonymous Coward]

I would expect "full-spectrum" lighting to include strong X-ray, ultra-violet and microwave radiation. Who'd have thought that would have a negative effect on one's health... :)

Re:Bah, it just looks nicer!

[moof1138]

Color temperature and 'full spectrum' are not really the same thing. A lot of cheap fluorescents have a low color temp around 2700 that looks yellowish, but you can buy fluorescents that have a higher color temp. Depending on what you like 3500-4100 bulbs are out there that will put out light that looks 'whiter', though if you go high you get a bluish look about 4500.

it's because of your flourescent bulbs

[SuperBanana]

However, we use full-spectrum bulbs a few places around the house, anywhere we don't have flourescent bulbs. Why? It just looks nicer! My SO and I can't stand the yellowness of regular bulbs, and we prever the whiter light of the full-spectrum guys, especially for reading and similar activities.

Siiigh. Okay, let me put my theatrical lighting designer hat on.

Your brain has a sort of biological "automatic white balance". It gets 'used to' different lighting so you 'see' the same colors.

This is both exploited by, and an annoyance for, lighting designers- if you have a very 'cool' scene, the next that follows will appear much warmer than it would to someone, say, walking in off the street.

The problem here is that you're used to the flourescent bulbs(which have a very high color temperature, ie, they're "cool" light- yes, it's odd). When you walk into a room with a regular incandescent bulb, your brain is 'calibrated' for the floursecent bulb and the light seems very warm. In the theater industry, there are specifically designed correction 'gels'(filters that look like they're plastic, but they're not- plastic would melt) for flourescent, HID and incandescent bulbs to make them 'look' like other light sources, or at least get them to a common baseline to then further color them with another gel.

This effect works in other ways- headlights look yellowish during the day but bright white at night. People driving cars with HID lights see 'normal' headlights as looking very yellowy; we see the HID lights as looking very blue.

If you want to see the effect yourself, find some lightly colored plastic, preferably light blue or light orange. Hold it over one eye, with the other closed, and after a minute or two, remove the plastic and note how the room looks different lighting-wise...