Out of the dark, how daytime light influences sleep and supports circadian rhythms

Sleep and circadian disruption is widespread, impacts health and blights lives. Light is the key regulator of sleep and circadian systems, and, in humans, bright days can enhance circadian amplitude, maintain wakefulness and reduce sensitivity to disruptive nighttime light. Elucidating underlying principles and mechanisms for these beneficial effects would provide the theoretical framework to understand relationships between light and health and reveal new targets for disorders of attention, sleep and circadian rhythmicity. Unfortunately, common laboratory rodents cannot model the human experience of light being nocturnal and photophobic. We’ve therefore established foundational knowledge and advanced experimental approaches for a light-seeking day-active murid (Rhabdomys pumilio). Rhabdomys recapitulate therapeutic benefits of daytime light providing a unique opportunity to establish: 1) the impact of brighter days on circadian rhythms and sleep from molecules to behaviour; 2) the underpinning cell and circuit mechanisms; and 3) the pre-clinical insight to inform interventions. In doing-so, we will extend understanding of circadian and sleep physiology to account for fundamental aspects of human biology; inform therapeutic and architectural application of light; identify new approaches to modulate influential aspects of physiological/behavioural state; and develop tools and resources to support adoption of Rhabdomys as a more translatable model in discovery research.