Associations Between Daytime Light Exposure and Mood, Vitality, Work Efficiency, and Sleep: A Field Study in Offices

This field study investigates the associations between office employees’ daytime light exposure and their experiences and behavior across multiple days. The study recruited 15 participants in real office environments and lasted for three weeks. Light exposure was recorded using wearable light sensors, sleep data were collected via wristbands, and experiences were gathered through four questionnaires every in-office working day. The analysis revealed that higher average illuminance over the past half-hour was positively related to self-reported positive affect, vitality, and work efficiency. Illuminance above 250 lx significantly improved vitality and morning work efficiency. Additionally, longer time exposed to illuminance above 250 lx during the day also facilitated quicker sleep onset at night. This study provides empirical evidence of the positive effects of bright daytime light exposure on office employees’ performance and sleep.