The recently discovered non-image forming (NIF) visual pathways are central to human experience. They project to over a dozen distinct brain regions to drive the way we see, think, feel, and sleep. This NIF pathway is uniquely suited to signaling slow daylong changes in light level, but also receives temporally precise inputs from rod and cone photoreceptors. The interactions between these pathways are poorly understood and so Dr Joyce probed the NIF pupil pathway to demonstrate the spatial, temporal, and adaptation properties of NIF vision in health and disease. Dr Joyce then leveraged the unique sensitivity of NIF vision in a sleep context, mapping the dose-response relationships between the intensities and durations of sequences of millisecond-scale lights with circadian rhythm phase shifts. Dr Joyce found that the circadian system can be “hacked” by extraordinarily dim and brief light flashes. These studies reveal temporal modulations of light are effective interventions to drive changes in NIF-linked behaviors, and their potential as physiologically targeted “photoceuticals”.
Dr Daniel S. Joyce is a Postdoctoral Scholar in Psychology at the University of Nevada, Reno, and studies the way that light affects human health and wellbeing. He draws from the fields of vision and circadian sciences to understand how light is sensed and interpreted by the brain for non-image forming functions. Such functions include setting circadian rhythms for restful sleep as well as optimizing mood and cognitive performance based on the time of day. He uses this knowledge to understand how dysfunction in this system contributes to diseases of ageing and to develop humancentric light environments that maximize health and wellness.