The third photoreceptor in the human eye and its meaning for lighting

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The third photoreceptor in the human eye and its meaning for lighting

Bommel, W. van

For more than 150 years, scientists considered rods and cones to be the only photoreceptor cells in the eye. Seen in this historic context, it is sensational that in 2002 David Berson et al. of the Brown University (USA) detected a novel, third type of photoreceptor in the retina of mammals. This novel photoreceptor is a 'missing link' in describing the mechanism of biological effects as controlled by light and darkness. With the detection of the novel photoreceptor cell in the eye, the biological effects that light has on human beings can be better understood. The spectral sensitivity of the novel cell type has in the meantime been studied and shows that bluish light has biologically a larger activating effect than does reddish light. These phenomena have an important meaning for the specification of healthy and 'alerting' lighting. They point to new ways to keep people alert. A possible application can be interior car lighting with deep blue lighting to keep night drivers alert. To demonstrate the practical importance this paper describes, from a wealth of research results available from the working environment, some examples of the influence of different lighting installations on health, alertness and well-being of people. In a working environment, not only are the advantages in terms of health and well-being important for the workers themselves, they also lead to better work performance, fewer errors, better safety, and lower absenteeism. An example from an industrial environment demonstrates that by changing the lighting from 300 to 500 lux may easily increase the overall productivity by 8 per cent.