The significance of lighting cannot be overlooked when considering your learning environment. Physiologically, the retina of the human eye accounts for 40 percent of all nerve fibers connected to the brain, which may account for the high number of visual learners in any group. This fact points to the need to do whatever possible to stimulate those nerves effectively. By providing natural or effective artificial lighting along with other visual stimuli, you can help improve the chance that learners will be more alert and take in more information.
Light affects the level of alertness a person has by limiting the amount of melatonin produced by the body. This natural substance causes drowsiness. Researchers have found that sunlight, and to some extent certain forms of artificial light, also impact responsiveness and mood, help cure rickets, reduce infections and colds, and can generally lead to better health. Studies on the impact of light in a variety of settings have resulted in some important discoveries related to human performance and physical and mental conditions in humans. Such research has also caused many school systems and organizations to rethink and retool the lighting in classrooms and work areas. For example, one study by a Vermont psychiatrist15 on the impact of lighting in three elementary schools found that lighting impacted absenteeism. In the experiment, London changed the light bulbs in a number of classrooms from standard to full-spectrum (Vitalite) to better simulate sunlight. According to London, when comparing absentee rates before and after the switch it was noted that absenteeism decreased by 65 percent following the change. Reportedly, fluorescent lighting raises the level of a hormone called cortisol in the blood. This substance suppresses the immune system and impacts stress, and increased levels can potentially adversely impact learning.
Even with all the research indicating the importance of light, many organizations have not gotten the word. For example, many conference facilities and training rooms often have lighting that is aesthetically attractive (e.g., chandeliers, recessed lighting, or sconces on the walls), but not functional from a learning perspective. Although such light fixtures may be attractive, they often do little to illuminate the room and to aid vision. In fact, they often detract from the learning experience because of reduced visibility, shadows, and darkened areas of the room.
In an internal report from the Institute for Research in Construction,16 D. Downing reported that "There is no area of our mental and bodily functioning that the sun does not influence. Our bodies were designed to receive and use it in a wide range of ways. We were not designed to hide from it in houses, offices, factories and schools. Sunshine, reaching us through our eyes and our skin, exercises a subtle control over us from birth to death, from head to tail." Assuming that Downing is correct, we should strive to make our training environments rich in light, either natural or artificial, or a combination of both.
An important point to remember is that all artificial light is not equal. Depending on the type of bulbs used, learners will receive more or less light value. Many artificial bulbs are designed to reproduce a wide spectrum of lighting compared to natural sunlight, which has a 100 rating on the color rendition index (RDI) used to rate various artificial light sources. Higher light ratings equate to a more positive benefit. In comparison to full-spectrum sunlight, incandescent lights emit red and yellow light, but radiate little energy in the blue and green region of the spectrum whereas cool-fluorescent bulbs emit mostly green and yellow bands. The blue-green part of the light spectrum is the most beneficial to humans.
Although it seems clear that lighting can definitely impact learning, the extent of such influence is subject to interpretation. As with any research, there is sometimes inconsistency and lack of experiment control. According to a comprehensive overview of scientific literature on behavior, performance, mental well being, and physiology,17 there is room to question the direct correlation of the amount of impact of artificial light sources on humans. Still, you may want to do as much as possible to provide adequate lighting for your learning environment. This means reducing or limiting glare and shadows, and reducing eyestrain while allowing ease of vision.
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