A review of applications of electroencephalogram in thermal environment: Comfort, performance, and sleep quality

The thermal environment significantly influences human health and productivity. The incorporation of electroencephalogram (EEG) signals, which reflect both physiological and psychological aspects, is increasingly prevalent in related studies. A comprehensive review of 73 studies investigates the intricate relationship between EEG signals, thermal conditions, and individuals. These studies primarily concentrate on thermal comfort, performance, and sleep quality. Time and frequency domain features of EEG signals have become common indicators for analysis. Notably, reduced EEG power is linked to thermal comfort, particularly in the frontal lobe. Employing EEG power ratios effectively evaluates cognitive load under various thermal conditions, achieving the classification accuracy exceeding 74.60 % through machine learning. The impact of the thermal environment on sleep quality has garnered considerable attention. The heightened slow wave sleep (SWS) indicates better sleep quality. While 70 studies were conducted in controlled chambers, predominantly with young college students, it is recommended to broaden the application scenarios to include outdoor and underground spaces. Considering variations in thermal environments and adaptations, expanding the sample size is also advisable. To advance the application of EEG signals in thermal environment research, developing open and high-quality datasets and adaptive thermal comfort recognition models is essential. Future research should focus on exploring correlations between the thermal environment and the power of different brain regions and frequency bands.