Abstract: The concept that certain wavelengths of light can change regional brain activity as well as influencing the functional connectivity between different brain centers, is rather striking. Such a concept goes beyond that of a function for light stimulating specialized retinal ganglion cells to entrain circadian rhythms but extends this to include light having a direct influence on all neurons to potentially influence a range of core higher-order brain activities. In this perspective, we explore how light may influence such core brain activities, together with why it should do so in the first place. We propose that the effect of light on brain activity has evolutionary links, relating to a basic survival strategy against any potentially dangerous situation.