Elsevier

Applied Ergonomics

Volume 37, Issue 4, July 2006, Pages 461-466
Applied Ergonomics

Non-visual biological effect of lighting and the practical meaning for lighting for work

https://doi.org/10.1016/j.apergo.2006.04.009Get rights and content

Abstract

The effects of good lighting extend much further than we used to think. Recent medical and biological research has consistently shown that light entering the human eyes has, apart from a visual effect, also an important non-visual biological effect on the human body. As a consequence, good lighting has a positive influence on health, well-being, alertness, and even on sleep quality. Our better understanding of the diversity in lighting effects teaches us that new rules governing the design of good and healthy lighting installations are required. Thanks to the recent discovery of a novel photoreceptor in the eye and its probable distribution within the eye we can now begin to define these new rules. These will guide us to dynamic lighting installations: that is to say dynamic in lighting level and dynamic in tint of whiteness of the lighting colour.

Section snippets

Three types of photoreceptor cells in the eye

For more than 150 years, scientists considered rods and cones to be the only photoreceptor cells in the eye. Fig. 1 shows the nerve connection between cones and rods in the retina of the eye and the visual cortex of the brain from where the sensation of seeing originates.

The sensitivity of the cone and rod systems varies with varying wavelength of light, and thus with varying colour of light. This is illustrated in Fig. 2, where the dotted curve gives the spectral eye sensitivity curve (Vλ) for

Non-visual biological effects related to light

We normally think of the eye as an organ for vision, but due to the discovery of additional nerve connections from recently detected novel photoreceptor cells in the eye to the brain, it is now understood how light also mediates and controls a large number of biochemical processes in the human body. The most important processes are related to the control of the biological clock and to the regulation of some important hormones through regular light–dark rhythms as for example the 24 h rhythm of

Health-related quality aspects of lighting installations

From the above, it is evident that the total visual environment has a direct connection with health. Different professions are involved in determining the visual environment. Architects determine the daylight penetration possibilities by the orientation of the building and the design and shape of windows. Interior designers determine the reflection and absorption of both day and artificial light by the colours of ceiling, walls and furniture. The lighting designer determines the link between

Lighting and productivity

We are now much better able to understand why the benefits of good lighting at work, taking into account both the visual effects and the non-visual biological effects (viz. health, well-being and alertness), are so important. Apart from the health and well-being advantages for the workers themselves, good lighting also leads to better work performance (speed), fewer errors and rejects, better safety, fewer accidents, and lower absenteeism. The overall effect of all this is: better productivity.

Conclusion

At the beginning of the industrial revolution, most people moved away from an outdoor daytime environment to an indoor daytime environment. The consequence of this was 40–200 times less light for those not working very close to a window. We have now learned that this has a negative influence on health and well-being. However, thanks to the recent discovery of a novel photoreceptor in the eye and the understanding of the mechanism responsible for non-visual biological effects, we are now able to

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