New dimensions of daylight and health: How opsin biology may inform lighting standards in the near future

Abstract

There have been many advances in our knowledge of how daylight exposure impacts human health since the discovery of the role of melanopsin in circadian entrainment over 20 years ago. Now, recent discoveries about other photoreceptors, collectively called opsins, promise to launch yet another revolution in our thinking about light and health. A wealth of evidence, from epidemiological, laboratory and clinical studies has outlined newly identified cellular and neurological functions dependent upon patterns of light exposure that could have important consequences for human health, such as metabolic diseases, mental health and eye development. This paper focuses on the significance of two additional non-visual opsins (Opsin 3, or Encephalopsin, and Opsin 5, or Neuropsin), which have peak responses to very short wavelengths of light in the blue-violet range. These wavelengths are abundant outdoors, in unfiltered sunlight and daylight, but are deficient indoors, as they are not emitted by most electric light sources and are also filtered out by some modern glazing materials. Similarly, they are missing in current daylighting metrics and measurement tools. This paper considers some of the implications for the design of the built environment and directions for new regulations and analysis that could help balance current concerns for energy efficiency and carbon reduction with human health and well-being.