Evolution of physiological, psychological, perceptual, and cognitive performance during a seven-day residence in underground working environment

Some occupational groups have to work and live in underground spaces for prolonged periods. Many complaints are raised, despite the environment being designed like above-ground buildings. Understanding the responses of residents during their stay in such an environment is therefore crucial for improving the design. This study explored the evolution of human subjects’ physiological, psychological, and cognitive performance in real underground over seven days. Significant changes in physiology (pulse rate, diastolic blood pressure, body temperature), cognitive performance (sustained attention, executive function, and mental calculation ability), and sleep conditions occurred on the 4th day. Psychologically, emotions deteriorated cumulatively, mainly manifested by a decrease in vitality (ρ = -0.93) and the accumulation of fatigue (ρ = 0.82). The Total mood Distress index showed a significantly positive correlation with PSQI scores (p < 0.001), indicating that worse mood was associated with poorer sleep quality. Notably, the skin temperatures in the head area (forehead, cheek, neck) were more sensitive to state changes, and cheek temperature (changing from 32.4 ± 1.0°C to 33.3 ± 0.8°C) could be a potential physiological indicator. With the underground environmental parameters maintained within the recommended ranges of above-ground buildings, the most substantial impact on the overall comfort of long-term residents was spatial comfort (β = 0.456, p = 0.001), followed by thermal comfort (β = 0.265, p = 0.007) and air comfort (β = 0.228, p = 0.010). This study shows the underground environment's effect on human health, providing basic information for improved environmental design and occupancy plans.