Understanding light's regulation of mood and arousal

Light is a powerful multifaceted stimulus; besides supporting vision, light is critical for a range of 'non-visual' responses, ranging from regulation of internal circadian rhythms to direct changes in mood and behaviour. This has direct implications for human health and well-being since one of the biggest differences in human lifestyle over the last decades is the time spent indoors exposed to artificial lighting of various qualities (>90%) and in front of screens of various devices (>10h/day). However, despite widespread appreciation that light influences mood and arousal, we still lack a basic understanding of the mechanisms involved. What types of visual signals are most important in regulating our mood and arousal state? What brain regions and circuits regulate these effects? Answering those questions will ultimately allow us to use light to gain control of these fundamental aspects of our biology and psychology. It will allow visual displays and lighting systems to be used to improve the well-being of the general population and to maximise the potential of light therapies in treating mood-related disorders.