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Light can vary dramatically in spectrum even is it is classified as the same color temperature. Light from LED and fluorescent sources is very different than incandescent lighting, even if they look the same on the surface.

Not all “Soft White” is equal

Whenever there is an article published on blue light and LEDs, someone will leave a ignorant comment. Usually they are saying that the article is total crap because LEDs are now available in soft colors and look just like their old bulbs. What they don’t know is that visible light can differ dramatically even if it appears to be the same. Take a close look at this chart from the Department of Energy. It compares the light spectrum from four different 2700K “soft white” light sources: halogen incandescent, compact fluorescent, and two types of LEDs.

Same color - Different Spectrum

We can see the dramatic difference between the halogen incandescent and all the others. Notice the peak in the blue portion of the spectrum for both types of LED lamps. You’ll also notice that incandescent lamps put out huge amounts of red and infrared light. Visually the same but drastically different “under the hood”.

Non-visual Receptors

Your eyes contain specialized receptors (Photosensitive retinal ganglion cells) that provide no visual information. Their sole purpose is to transmit information about the amount of blue light in the environment. This information is relayed directly in to the suprachiasmatic nuclei (SCN). Also known as the body’s Master Clock. These receptors are stimulated by all light but are vastly more sensitive to blue light. Interesting fact: There are people who are completely blind that still have perfectly functioning retinal ganglion cells taking in information on lighting conditions! Light intensity and color spectrum are continuously calibrating the body’s master clock.

All things being equal, CFLs and LED lighting will stimulate your retinal ganglion cells more than incandescent lamps. This is a problem.

Black-Body Radiation

Though out all the millions of years of life on earth, lighting came from back body radiation. The sun. You know what else is a black-body radiator? Incandescent lamps and fire.
Very simply, black-body radiation is electromagnetic radiation that is emitted from heat. A portion of that radiation is visible light. A much greater portion is infrared light. You can read more about black-body radiation on Wikipedia.

If we do away with incandescent lighting, our only significant exposure to far-red and infrared light will be from the sun. Unfortunately we spend a huge portion of our lives indoors and that is not likely to change any time soon.

The question is: What are the consequences of removing far-red and infrared light from our environment?

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