Therapeutic Lighting Design to Decrease Depression in Older Adults

Depression is a common symptom in older adults with the estimated prevalence of 5-15% among those residing in community dwellings. Lighting in buildings is one main environmental attribute that plays a significant role in managing behavioral and psychological symptoms through impacting visual and circadian systems. 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. This study aimed to evaluate the effects of two whole-day ambient lighting interventions on depression in older adults. Both lighting interventions were designed to create a direct/indirect ambient illumination that provided a high illuminance level (500 lux) in the morning (8:00 – 12:00) and then the illumination was dimmed gradually throughout the day and reached 100 lux in the evening (after 20:00). One lighting condition (L1) delivered a constant Correlated Color Temperature (CCT) of 2700 0K. In the other lighting condition (L2), the CCT was changing in a range of 6500 0K – 2700 0K from morning towards evening. Fourteen healthy older adults (mean age = 73.2 years; 11 female), from two senior residential communities in Saint Louis, Missouri, participated in a counterbalanced crossover study. Participants were exposed to each lighting condition 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.

https://doi.org/10.35483/ACSA.AM.108.14

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ISBN
978-1-944214-26-5