Light at Night

We know that light affects humans in at least two ways: it enables us to see and it regulates our biological rhythms that repeat approximately every 24 hours, called circadian rhythms.

There is a growing interest in the role that light plays on human health, particularly nighttime exposure to short-wavelength (blue) light. The interest in short-wavelength light is that it might reduce melatonin production at night or disrupt the internal body clock and, perhaps thereby, increase the incidence of disease. Although a logical link may exist between light at night and diseases, it is important to point out that an empirical, scientific link between light at night of a given amount and spectral composition, and an increased risk of disease in humans has not yet been made.

Several years ago, the LRC anticipated much of the current discussion on light at night as it might affect human health. In fact, this topic is one of the LRC’s core research efforts funded by several government entities and the private sector. We are gratified that so many leaders in government and the private sector believe, as we do, that good science and sound measurements are the only paths to rational deliberation on public policy regarding the impact of light at night on human health and well-being. It is simply too soon to conclude that light at night, blue or otherwise, has any impact on human health, particularly claims that are unsubstantiated by actual measurements of the light-dark pattern experienced by people. Similarly, it is too soon to claim that light at night has no impact on health. Understanding what these effects might be has been the thrust of the LRC's research in this area.

The LRC’s research is available for public consumption and we encourage anyone interested to review the research and educate themselves on all sides of the issue.

Following are three suggested papers published in peer-reviewed journals summarizing just some of LRC’s research on the subject of light and health:

Does Architectural Lighting Contribute to Breast Cancer? - Scientific paper published in the Journal of Carcinogenesis.

Of Mice and Women: Light as a Circadian Stimulus in Breast Cancer Research - Scientific paper published in Cancer Causes and Control.

The Daysimeter: A Device for Measuring Optical Radiation as a Stimulus For The Human Circadian System - Scientific paper published in Measurement Science and Technology.

To learn more about the LRC’s Light and Health Program, please visit www.lrc.rpi.edu/researchAreas/healthVision.asp.