'Biological mechanisms underlying the impact of visual stimuli on mood and affective state'

"The WHO predicts mental health problems to be the leading cause of mortality and morbidity globally by 2030. In the last decade, evidence has emerged that the visual system represents a new neurophysiological pathway regulating mood. Understanding how visual stimuli influence mood and affective sate is very timely because people now spend >90% of their time indoors exposed to artificial lighting, and >10h/day in front of screens of numerous devices (TVs, phones, computers). Encouragingly, light can be used as an effective and non-invasive therapeutic option with little to no side effects, to improve sleep, mood, and general well-being. Light therapy is the treatment of choice for seasonal affective disorder and is emerging as a treatment for other psychiatric disorders(1,2).
We are at an early stage of understanding the visual system's ability to influence mood and affective state. So far we know that bright and blue light increases arousal in humans, and the supervisory team has shown that at least part of this effect can be attributed to a specific type of retinal cells in our eyes(3,4). But our visual environment is more complex and it would be naïve to think that scene brightness is the only visual sensation that can impact mood. However, we still do not know what types of visual signals are most important in regulating mood and what are the underlying biological mechanisms. "