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Abstract We investigated the effect of illuminance and correlated colour temperature (CCT) on the subjective evaluation of users' reading behaviour in a narrow space (i.e. a capsule hotel). Participants (N = 18; 15 men, 3 women; mean age = 21.9 years, SD = 0.4 years; age range = 21–23 years) were Japanese university students and graduate students. Experiments were conducted within four behavioural conditions that differed in six distinct illuminance (i.e. 150 lx and 300 lx) and CCT (i.e. 2800 K, 5000 K, and 6700 K) combinations. Because of the subjective evaluation of the space using the 7-level semantic differential method, participants did not experience pressure in the experimental space when it satisfied illumination standards. Sense of security was significantly influenced by CCT rather than illumination. Higher CCT was associated with higher spatial brightness. Lower CCT was associated with a higher sense of security, restfulness, and positive feelings. Brightness, sense of security, restfulness, feelings of fatigue, and concentration were all significantly impacted by the behavioural conditions. These findings suggest that providing a user-friendly and user-controlled lighting system will likely increase the satisfaction individuals experience when staying in a capsule room. Highlights • We investigated the impact of lighting behaviour in a small confined space. • Pressure was not perceived if illumination standards were met. • Perceived brightness was related to users' behaviour (reading vs. resting). • Correlated colour temperature impacted users' sense of comfort in a confined space. [ABSTRACT FROM AUTHOR]

This study provides optimal correlated color temperature and illuminance to increase comfort and reduce fatigue by considering psychological and physiological quantities when working with paper and electronic devices. Task performance was not affected by devices and lighting conditions. The subjective evaluation revealed no significant differences between devices. The participants felt tired with an illuminance of 300lx and preferred a correlated color temperature of 5000K or 6500K and an illuminance of 750lx. However, the participants were more comfortable at 3000K and 750lx than at high correlated color temperature and low illuminance. The adjustment method demonstrated that comfortable illuminance does not show a significant difference in correlated color temperature and that paper requires significantly higher brightness levels than a screen. The adjustment method and subjective evaluation found consistent results for comfortable illuminance. Physiological measurements revealed that oxygenated hemoglobin was higher for computer than for paper use. In addition, illuminance of 500lx and correlated color temperature of 5000K resulted in the least fatigue. Although the subjective evaluation found no significant differences in fatigue, physiological measurements revealed that illuminance and correlated color temperature were accompanied by the least fatigue. Therefore, the results of this study highlight the necessity of creating a work environment that considers psychological and physiological quantities based on the work medium. • Illuminance and color temperature with computers and paper were examined. • Objective and subjective measurements were used for comfort and fatigue. • Comfort level with different types of lightning was identified. • Differences between perceived and measured comfort were found. • The importance of device and task content was discerned. [ABSTRACT FROM AUTHOR]