LESA Researchers Agung Julius and Mona Hella received $750K in funding to further develop a novel approach to estimate circadian phase shift through the use of dynamic lighting applications and biosensing wearables. Circadian rhythms are regulated by an internal biological clock that synchronizes biological processes with the daily light and dark pattern. Disruption of circadian rhythms has negative impacts on human health and wellbeing. LESA researchers have long studied the effects of circadian phase disruption. In this project, Hella and Julius will develop wearables enabled with signal processing algorithms for use in model identification and state estimation of the circadian system and related neurocognitive processes. The state estimation algorithms will use tools from control theory and machine learning and combine model-free and model-based approaches. The validity of the hardware and software developed in this project will be evaluated in the LESA Healthy Lighting Testbed at Thomas Jefferson University Hospital in Philadelphia through controlled in-lab experiments with the assessment of dim light melatonin onset in healthy human subjects.