Effects of lighting on ECG, visual performance and psychology of the elderly

Research has explored the effects of illuminance and correlated color temperature (CCT) of indoor lighting on visual performance, mood and physiological parameters of the elderly. Yet, these investigations did not render a consistent finding on visual and non-visual effects of lighting from a holistic perspective. The present study systemically explored the comprehensive effects of illuminance (300 lx, 500 lx, 750 lx, 1000 lx and 1500 lx) and CCT (3000 K, 5000 K and 6500 K) on electrocardiogram (ECG), visual performance and subjective mood of the elderly. The findings revealed that the ECG indicators of the elderly did not change significantly under most lighting conditions though the heart rate was more sensitive to light than waveform time. In addition, an increase in CCT elicited statistically significant benefits on task performance, however, participants' task performance was not significantly enhanced with the increase of illuminance, and the light of 750 lx seemed to be the most unfavorable for the visual task of the elderly. Furthermore, the participants' subjective appraisals were inclined to be positive and satisfactory and were not significantly different between different lighting conditions. The results of this study showed that short duration (i.e. 20 min) of light exposure had little effect on the physiological rhythm of the elderly, but it did affect the visual performance and psychological feelings of the elderly. Therefore, in the places where the elderly stay for a short time, the first consideration of lighting design should be to meet the visual and psychological needs of the elderly.