A study of tunable lighting at the ACC Care Center, a 99-bed nursing center in Sacramento, CA, with a large population of dementia patients. The study involved a partnership between experts in lighting design, environmental design, and light measurement; experts in measuring resident behavioral outcomes in nursing centers; and leaders from a nursing center with previously installed programmable, tunable LED lighting. The objective was to test a strategy for measuring and documenting light exposure for typical nursing-center residents, and to evaluate the data in terms of various metrics for human circadian responses over the course of a day. The study builds on a prior field evaluation of tunable lighting at the ACC Care Center.