Lighting up living spaces to improve mood and cognitive performance in older adults

Recent studies reported that bright light exposure can impact mood and cognitive functions in various age groups. However, these studies have not adequately addressed the effects of ambient lighting in living spaces on healthy older adults. In the present study, the effects of a whole-day lighting scheme were examined in residential units inhabited by older adults. The lighting condition (L_T) was designed to create a direct/indirect ambient illumination that delivered bright, blue-enriched light (illuminance level: 500 lx, Correlated Color Temperature (CCT): 6500 K) in the morning, followed by gradually lower illuminance levels and CCT throughout the rest of the day, reaching 100 lx and 2700 K in the evening. To further examine the effects of spectrum, we also included another lighting condition (L_P) with the same range of illuminance levels and constant CCT of 2700 K from morning to evening. Twenty-one healthy older adults (mean age = 76.81 years; 16 females) completed a counterbalanced crossover experiment, with two baseline measurements (before and after interventions) and eighteen days of interventions. Data were collected using standardized questionnaires and tests. Significant improvements were observed in mood and cognitive functions measured after exposure to both lighting conditions (L_P and L_T); there were significantly greater improvements for the L_T as compared to the L_P condition. This study found promising evidence that a whole-day lighting scheme that follows the natural light/dark cycle could be an effective design solution to create a healthy and healing living environment in living spaces and promote mood, cognitive functions, and hence the quality of life in senior residents.