Paper Title
An Investigation of Light Spectrum and Intensity on Depression in Older Adults

Abstract
Building illumination impacts significantly behavioral and psychological symptoms through because its regulates our circadian system. Considering the age-related changes in eyes and the circadian system, specialized lighting design is essential to promote mood and overall well-being in older people. Depression is a common symptom in older adults with the estimated prevalence of 5-15% among those residing in community dwellings. This study aimed to evaluate the effects of two whole-day ambient lighting interventions on depression in older adults. Both lighting interventions are designed to create an ambient illumination that provides a high illuminance level (500 lux) in the morning (8:00 – 12:00) and then the illumination is dimmed gradually throughout the day and reached 100 lux in the evening (after 20:00). Participants were exposed to two different lighting conditions for 9 days. Using the Geriatric Depression Scale to measure depression levels before, during, and after lighting interventions we found a significant decrease in depression after exposure to both lighting conditions; there was more reduction for the L2 intervention. These findings illustrate the beneficial effects of adding varying illumination and spectrum to the ambient lighting quality in residential buildings. Given that older adults spend the majority of their time indoors, designing whole-day ambient lighting with varying intensity and tuning spectrum could be an effective therapeutic solution to create an antidepressant environment and improve quality of life in older adults. Keywords - About Four Key Words or Phrases in Alphabetical Order, Separated By Commas.