EEG-based evaluation of illuminance and correlated color temperature adjusted to fatigue levels in a VR residential environment

Fatigue directly affects quality of life, but its causes and treatments remain unclear, and managing it with sufficient rest is essential. This study evaluates fatigue-based lighting (FBL), a system that adjusts illuminance and correlated color temperature (CCT) to alleviate fatigue. In a virtual reality (VR) one-room apartment, electroencephalogram (EEG) signals were measured from 24 healthy adults (11 men, 13 women; aged 24–43 years), yielding 28 valid datasets. Participants were first exposed to a standard lighting condition (300 lx, 6000 K). After a short rest, they were exposed to one of three FBL conditions based on their fatigue level: level A (“a little tired”: 400 lx, 5000 K), level B (“tired”: 500 lx, 4000 K), or level C (“very tired”: 150 lx, 3000 K). EEG changes before and after exposure were analyzed using the Alpha/Beta Ratio (ABR), an indicator of relaxation. The mean ABR increased at 17 of 19 electrodes, suggesting a positive effect on fatigue relief. Significant increases were found at five electrodes (FP1, FP2, F7, T4, O1), corresponding to the frontopolar, frontal, temporal, and occipital regions. Further analysis showed that ABR values at FP1, F7, and T4 increased significantly (p < 0.05) under fatigue level B, implying that lighting at 500 lx and 4000 K may have the potential to alleviate fatigue at this level. These findings provide neurophysiological evidence that lighting tailored to fatigue level can promote recovery and highlight the potential of personalized, adaptive lighting systems for human-centric design in residential and occupational environments.