Stuart’s research focuses on how the light environment regulates physiology and behaviour. The vertebrate retina contains photoreceptors that mediate the dual tasks of vision and monitoring environmental irradiance (brightness). Environmental light modulates numerous different processes in our bodies, including the circadian clock, sleep/wake timing, pupil constriction, hormone synthesis, heart rate and cognitive performance. The central aims of our work are to understand how light information is transmitted from eye to the brain and the neural and molecular signalling pathways involved. Understanding how light affects our bodies is critical to appreciate how the modern artificial lighting environment may impact upon our health and to determine how we can optimise lighting to the demands of the 24/7 society.