The light we experience in our daily lives has a major impact on our body rhythms. Modern lifestyles, with 24-hour electric lighting and reduced exposure to natural light, can disrupt sleep and negatively impact health, well-being and productivity.
Professor Timothy Brown from the University of Manchester in the UK and Kenneth Wright from the University of Colorado Boulder in the US have brought together a group of leading international scientific experts to agree on the first evidence-based consensus recommendations for healthy day, night and nighttime light exposure. These recommendations provide much-needed guidance to the lighting and electronics industries to help design healthier environments and improve the way we light our workplaces, public buildings and homes.
One key question the new report addresses is how to properly measure the extent to which different types of lighting affect our body rhythms and daily sleep and wake patterns. Light affects these patterns through a special type of cell in the eye that uses a light-sensitive protein called melanopsin, which is different from the proteins in the rods and cones that support vision (on which traditional methods of measuring "brightness" are based). Because melanopsin is most sensitive to light in a specific part of the visual spectrum (blue-cyan light), the new recommendations use a newly developed light measurement standard that specifically targets this unique property, known as melanopsin equivalent daylight illuminance. Analysis of data from a range of laboratory and field studies proves that this new measurement method can provide a reliable way to predict the effects of light on human physiology and body rhythm, and can therefore form the basis for widely applicable and meaningful recommendations.
An important next step is to incorporate these recommendations into formal lighting guidelines, which currently focus on visual requirements rather than impacts on health and well-being. In addition, with the increasing maturity of LED lighting technology and the availability of low-cost light sensors, it is expected that individuals can more easily optimize their personal lighting to best support their body rhythms according to the new recommendations.
Brown added, "These recommendations provide the first scientific consensus, quantitative guidance for appropriate daily light patterns to support healthy body rhythms, nighttime sleep, and daytime alertiness." This now gives us a clear framework for how we can illuminate any interior space, from workplaces, educational institutions and medical facilities to our own homes."
