The mammalian eye serves both visual and non-image-forming functions. New information about the non-image-forming anatomy and physiology of the eye has revealed effects of ocular light stimuli on human circadian rhythms, melatonin suppression, heart rate, pupillary reflexes, cognitive performance, alertness and sleep. The results of the proposed work can be used to make predictions about the effects of light, to make recommendations involving exposure to or avoidance of light, and to design environmental lighting, resulting in improved health and alertness and decreased errors and accidents.