Project Summary This proposed project will develop and field-test a device that accurately monitors and controls the circadian stimulus (CS) for Alzheimer disease (AD) and Alzheimer-disease-related dementia (ADRD) patients in nursing homes. Human biology has evolved to have two distinct optical systems: the visual system, by which we see and process images, and the circadian system, which regulates our biological clock and associated biological systems. These two systems have significantly different spectral and temporal responses to optical input. Specifically, circadian stimulation peaks at 460 nm and responds after several minutes of optical activation, while the visual system peaks at 555 nm and responds nearly instantaneously to inputs. While a broad and growing body of research has documented the impacts the circadian system has on human health, including regulating sleep and improving cognition in AD/ADRD patients, research on the CS experienced by AD/ADRD patients is extremely limited. All lighting systems are designed and installed in buildings with consideration only given to the photopic (visual) system and all light meters used to characterize lighting buildings are calibrated to measure photopic light, not CS. Researchers at the Lighting Research Center at Rensselaer Polytechnic Institute developed the Daysimeter, a calibrated light meter that measures circadian light and circadian stimulus. In the proposed project, researchers would modify an existing workstation-based lighting control system they previously developed for the visual system to include Daysimeter technology. This modified lighting controller would include the all the necessary sensors and components to monitor and control both circadian and photopic light and exposure to CS. Data from these devices would be wirelessly transmitted to researchers via an Internet gateway and associated cloud-based data management systems. These data would be of immediate value for gaining a better understanding of AD/ADRD patients' CS exposure and could ultimately result in new lighting systems and/or building codes that consider both our visual and circadian systems. After these modifications are completed and the devices are shown to accurately record CS in the laboratory, 20 prototype devices would be deployed in AD/ADRD nursing homes for one month. Data from these devices, other measurements made at the field site, and assessments of AD/ADRD patient sleep patterns, sleepiness, and depression would be collected. A final report would be prepared that includes: 1) recommendations for modifications to the device (if needed), 2) a discussion of correlations between measured CS and patient sleep, sleepiness and depression and, 3) plans for large field test deployment in Phase II.