Full-spectrum light
2403904
217390740
2008-06-05T20:45:54Z
KC Panchal
3449833
/* Independent verification */ added and populated the "See also" section
'''Full-spectrum light''' is light that covers the [[electromagnetic spectrum]] from [[infrared]] through near-[[ultraviolet]], or all wavelengths that are useful to plant or animal life; in particular, [[sunlight]] is considered full spectrum, even though the solar spectral distribution reaching Earth varies with time of day, latitude, and atmospheric conditions.
"Full-spectrum" is not a technical term when applied to an [[electrical]] [[light bulb]] but rather a marketing term implying that the product emulates natural light.<ref name="Galidakis">
{{Cite news
| volume = 7
| issue = 5
| title = Full-spectrum Light Sources
| work = Lighting Answers
| accessdate = 2007-11-01
| date = September
| url = http://www.lrc.rpi.edu/programs/NLPIP/lightingAnswers/fullSpectrum/abstract.asp
}}</ref>
Products marketed as "full-spectrum" may produce light throughout the entire spectrum, but actually do not produce an even spectral distribution, and may not even differ substantially from lights not marketed as "full-spectrum".<ref name="Galidakis"/><ref>{{Cite web
| last = Galidakis
| first = I.N.
| title = The Double Amici Prism Hand-Held Spectroscope
| accessdate = 2007-11-01
| url = http://ioannis.virtualcomposer2000.com/spectroscope/amici.html#fullspectrum
}}</ref>
[[Image:CIE illuminants D and blackbody small.gif|right|frame|Color of daylight and a blackbody, compared.]]
== Measurement ==
[[Color temperature]] and [[Color Rendering Index]] (CRI) are the standards for measuring light. In general, [[Kelvin]] temperature ratings of 5000 K or higher and CRI of 90 or higher denote a truer, full-spectrum light.
[[Image:Black-body-in-mireds-reversed.png|thumb|Color of a blackbody]]
A cube of [[carbon]] will radiate light of varying [[spectral power distribution]] (SPD) as it is heated. At 0 K, it is pure black, while at about 5,000 K to 5,500 K, it appears similar to noon daylight.
== Use in art and in color matching==
Full-spectrum [[fluorescent lamps]] are used in the [[Studio|art studio]] by [[artist]]s who [[Painting|paint]] pictures on canvas when they paint at [[night]] or inside (ideally, during the day the art studio should have north [[sunlight]], but many artists don't have access to north sunlight so they use full-spectrum lamps instead) in order to make sure that the colors they are using appear in their natural [[hue]] as they will appear when the painting is displayed in a [[home]] or in an [[art gallery]].
Full-spectrum lamps are also used by color scientists or color matchers in [[paint]] stores to match colors at night or inside when they don't have access to north sunlight.
== Use in gardening ==
[[Houseplant#Light|Gardening under lights]] keeps plants blooming almost year-round, for a wintertime harvest.
Some plants grow better when given more of a certain color light, due to the mechanism of [[photosynthesis]].
== Use in seasonal affective disorder ==
In recent years, full-spectrum lighting has been used in the treatment of [[seasonal affective disorder]] (SAD) through the use of "light boxes" that mimic natural [[sunlight]], which may not be available in some areas during the winter months. Light is an environmental stimulus for regulating [[circadian cycles]].
Lightbox therapy, otherwise known as [[phototherapy]], is a recognized modality for depression (such as SAD). Depending on the quality of the light, it is estimated that 10,000 [[lux]] is needed for effective treatment. Not all light boxes are the same. It is possible the [[phosphor]]s used to mimic the natural light emit harmful [[ultraviolet radiation]].{{Dubious|date=March 2008}}<!-- phosphors block UV generated from mercury? -->
=== Independent verification ===
The non-profit [http://www.lrc.rpi.edu/ Lighting Research Center], a group of utility companies, experts and government agencies, established the [http://www.lrc.rpi.edu/programs/nlpip/ National Lighting Product Information Program] (NLPIP) to provide objective information about the effectiveness of different lighting systems. According to the NLPIP, full-spectrum light does not provide any improved benefits over similar light systems.<ref>[http://www.apollolight.com/new_content/light_therapy/full_spectrum_controversy.html The Full-Spectrum Controversy] - Apollo Light</ref><ref>
[http://www.lrc.rpi.edu/programs/nlpip/lightingAnswers/fullSpectrum/abstract.asp Full-Spectrum Light Sources] - Light Research Center</ref> <ref> [http://www.sylvania.com/content/display.scfx?id=003680192 Sylvania's Statement on FS Lighting with US Gov links] Sylvania PDF</ref>
A Cornell study casts doubt on the use of full-spectrum lighting in restaurants to promote sales.<ref>{{Cite news
| title = Cornell study finds full-spectrum lighting has no effect on restaurant sales
| work = Cornell Chronicle
| accessdate = 2007-11-01
| date = 2007-09-14
| url = http://www.news.cornell.edu/stories/Sept07/restaurants.lights.RN.html
}}</ref>
== See also ==
* [[Sunlight]]
* [[Artificial sunlight]]
* [[Light ergonomics]]
== References ==
<references/>
* {{Cite journal
| last = Gifford
| first = Robert
| title = Scientific Evidence for Claims about Full-Spectrum Lamps: Past and Future
| url = http://irc.nrc-cnrc.gc.ca/pubs/fulltext/ir659/gifford.pdf
}} [http://web.uvic.ca/psyc/gifford/]
[[Category:Lighting]]
[[Category:Ergonomics]]