Effects of lighting on task performance, stress and thermal sensation in working environments

Studies have shown that the correlated colour temperature (CCT) of light significantly influences individuals engaged in study and work activities. However, the impact of CCT on stress and task performance, particularly when considering subjective preferences and experiences, has been explored only to a limited extent. This study aims to investigate the relationship between CCT, thermal sensation vote, stress levels and task performance. Forty-two healthy participants (21 female and 21 male, aged 20 to 53 years) participated in the experimental study. Participants completed a paper-based task and subjective questionnaires across three sessions, each conducted under different CCTs (2700 K, 4000 K and 6500 K). During these sessions, electroencephalogram (EEG) and heart rate variability were monitored to objectively assess stress levels. The study primarily focused on the activity of EEG alpha and theta waves in response to varying CCT degrees. Notably, significant activity was observed in the frontal lobes at 2700 K, particularly related to the frontal theta wave. Statistical significance was also identified in different brain regions in both alpha and theta waves among participants who demonstrated successful task performance. Additionally, participants reported optimal thermal comfort at 2700 K, which was associated with enhanced task performance and reduced stress levels.