Energy-efficient and Health Promoting Light for Elderly People

Lightning conditions seems to be important for the length and quality of sleep, as light have an influence on the production of the sleep hormone (melatonin) and the the circadian rhythm. Entrainment of the circadian rhythm to the surroundings is accomplished by light-sensitive retinal ganglion cells and these cells are sensitive to blue light. Based on previous research, blue light early in the day and abscence of blue light during evening is important for the entrainment. In this study, lightning conditions in the home of healthy subjects are set to either blue enriched or red enriched from 8 a.m to 1. p.m. The lightning condition is based on a randomization protocol in a cross-over study for 3 weeks in each condition, separated by a one week pause.