Blue Light, Pupil Dilation and Productivity

During the 1960's and 70's lighting experts noticed that different types of light sources, even when they had the same visual power, would result in significantly different levels of productivity. But they didn't know why. Finally, around 1990, Dr. Sam Berman and his colleagues at Lawrence Berkeley National Laboratory discovered the reason.

The strength of certain ranges of blue in the spectrum controls the dilation of the pupil. Colder lighting, or lighting with a lot of blue light, causes the pupils to contract more for a given level of light than does the same level of light of a warmer tone.

Pacific Gas and Electric has had some success using Dr. Berman's findings in an attempt to save electricity. Retrofitting entire buildings with a warmer light source, low in the critical blue spectrum, allows people to work efficiently with a lower actual level of light.

Blue Light and LED Lighting

LED's are effecient producers of light. More and more they are being used as the light source for our homes and businesses. Using LED's is somewhat complicated by the fact that all white LED's have a strong component of blue light. This blue light needs to be equalized by other light frequencies in order to create an acceptable white light source which does not lower productivity. The two common ways of creating the balancing light are to use

• other red, yellow and green LED's that balance each other out or
• a yellow phosphor that glows in the presence of a strong light.

Sources of LED lighting.