Psychophysiological Effects of Shooting Tree Light Colors on Alertness: A Controlled Laboratory Study

As an essential component of the built environment, outdoor artificial lighting at night, has a profound impact on visitors’ experience quality. Research on the light environment extends beyond visual effects to encompass broader psychophysiological impacts, such as perception, emotion, and public health. Shooting tree lights (STLs) are a distinctive type of outdoor lighting, commonly installed in landscape environments. This study aims to investigate the effects of different colors (yellow, red, green, and blue) of STL on alertness at night. Sixty participants took part in an experimental design assessing the impact of four different colors on electroencephalogram (EEG) and self-reported alertness. Our results indicate that STL color is a significant factor influencing physiological alertness levels. Exposure to yellow light reduced beta power, diminished alertness, and enhanced relaxation and comfort compared to red, blue, and green light. The study also identified variations in alertness based on age and gender. With respect to age, younger individuals exhibited greater alertness, while women were more alert than men. This study suggests that yellow light is generally more favorable than other colors in enhancing subjective light comfort. These findings underscore the importance of prioritizing yellow-colored STLs in landscape planning and design to promote relaxation and comfort for nighttime visitors.