Investigate the Effect of Age and Lights on Human Responses

The purpose of the study was to investigate the effect of age and lights on human responses. The participants included 10 young (22.40 ± 1.43 years old) and 10 middle-aged (36.40 ± 1.43 years old) adults. Independent variables of the experiment were groups (young and middle-aged adults), light environment (light A and light B) and time. Light A and light B were RGB LEDs; and the peak of blue spectrum was the only difference between light A (464 nm) and light B (451 nm). Dependent variables were physiological responses and subjective evaluations. The physiological responses included heart rate (HR), galvanic skin response (GSR) and little finger temperature. The subjective evaluations included feeling about lights (range from dim to bright), emotion and generalized anxiety disorder questionnaire (GAD). In this experiment, each participant should take a rest and feel the light environment for 40 min. The results showed that the age groups were the main factor to affect the physiological responses. The post-hoc comparisons showed that young adults were more relaxing than middle-aged adults. On interaction between age groups and lighs for GSR and HR, the reults showed that young adults felt more relaxed than middle-aged adults while at light A environment which was 464 nm peak wavelength of blue spectrum. Lights were the main factor to affect the subjective evaluations. All participants felt more dim, less tense, more serene and less GAD at light B than at light A. However, there was significant difference for only tense & jittery question and the others were significant trend (bright/dim, serene & contented and GAD). This study suggested that it was needed to consider the age and light factors when designing the light environment.