March 10, 2014
Science Daily/University of Liège
It has long been known that light exerts powerful effects on the brain and on our well-being. Light is not only required for vision but is also essential for a wide range of “non-visual” functions including synchronization of our biological clock to the 24h day-night cycle. A novel photoreceptor has now been shown to be an essential component for relaying light information to a set of so-called non-visual centers in the brain. Continuous changes in light throughout the day also change us, new research suggests.
The phenomenon of prior light effects on a subsequent response to light is typical of melonopsin as well as certain photopigments of invertebrate and plant, and has been referred to as a "photic memory." Humans may therefore have an invertebrate or plant-like machinery within the eyes that participates to regulate cognition. It may also explain what human chronobiologists have described as "previous light history effects," a form of long term adaptation to previous lighting conditions.
These findings emphasize the importance of light for human cognitive brain functions and constitute compelling evidence in favor of a cognitive role for melanopsin. More generally, the continuous change of light throughout the day also changes us. Ultimately, these findings argue for the use and design of lighting systems to optimize cognitive performance.