| 其他摘要 | With the prevalence of artificial light, the time for people working in indoor lighting environments is getting longer and longer, and the effects of light on people’s subjective feelings (emotion, comfort and visual fatigue) has received wide attention. The present study aimed to define the effects of multiple light characteristics on the subjective feelings of young subjects and to investigate its underlying mechanism, so as to provide theoretical basis and guidelines for designing the best light conditions in the field of health lighting and developing the most efficient clinical light therapy paradigm.
The current research consisted of three studies. Study 1 aimed to define the effects of short-term light exposure on subjective feelings. Experiment 1 adopted a mixed experimental design to investigate the effects of short-term exposure to white light on subjective feelings. The results showed that the effect of light intensity on comfort was affected by time-of-day. The comfort rating under 50 lx was significantly lower than 500 lx in the morning while the comfort ratings under 50 lx and 100 lx were significantly higher than 500 lx at evening. In addition, the comfort ratings under 500 lx in the morning and afternoon were significantly higher than at evening. Furthermore, the effects of light intensity on other subjective feelings and the effects of correlated color temperature on all subjective feelings were not significant. Experiment 2 also adopted a mixed experimental design to study the effects of short-term monochromatic light exposure on subjective feelings. The results showed that the main effects of monochromatic light wavelength on all subjective feelings were significant. We also found that, under monochromatic light with long wavelength (650 nm and 630 nm), the rating scores of emotional valence and comfort were the lowest while arousal and visual fatigue were the highest. Furthermore, the effects of wavelength on subjective feelings were not affected by time-of-day.
Study 2 aimed to study the effects of long-term light exposure on subjective feelings. In Experiment 3, we studied the effects of long-term white light exposure on subjective feelings. In order to increase the sensitivity of the measurement, the objective indicators that are commonly used to evaluate subjective feelings, such as brain electricity, heart rate, blood pressure, skin resistance, etc., were also measured during lighting. The results about subjective self-evaluation showed that, after 5 min lighting, comfort under 50 lx was significantly higher than 500 lx while arousal was significantly lower. However, there’s no significant difference in comfort and arousal among different illuminances after 45 min and 90 min lighting. The results about objective indicators showed that the diastolic and systolic blood pressure under 500 lx were higher than under 100 lx and 50 lx while the diastolic blood pressure under 6500 K was higher than under 5000 K. Under 500 lx, the power value of Delta, Theta and Alpha in Fp1 after 5 min lighting were significantly higher than after 45 min and 90 min lighting, and the power value after 45 min lighting was significantly lower than that after 5 min and 90 min lighting. The power of Delta, Theta, and Alpha in Fp1 under 100 lx after 45 min lighting was significantly lower than after 90 min. Experiment 4 studied the effects of long-term monochromatic light exposure on subjective feelings. The results showed that the interaction between light duration and monochromatic light wavelength on emotional valence, dominance, comfort and visual fatigue were significant. After 5 min lighting, there were significant differences in emotional valence, dominance, comfort and visual fatigue among wavelengths. However, with the increase of lighting time, the differences of emotional valence and comfort among monochromatic lights gradually disappeared, while the differences of dominance and visual fatigue among monochromatic lights were still existing.
Study 3 took the concentration of melatonin in saliva as the biochemical index of rhythm, to explored the pathway of light affecting subjective feelings using a mediation effect model, and to examine whether the effect of light on subjective feelings is related to the difference of eye structure. The mediating model analyses showed that the direct effect of light on subjective feelings were significant whereas the indirect effect of melatonin concentration on subjective feelings were not significant. To further explore the effect of eye structure on subjective feelings, we developed the mediating models by setting eye structure as covariates, and the results remained unchanged. These results suggested that the effect of 1 hour monochromatic light exposure or 1.5 hours white light exposure on subjective feelings is affected by direct pathway, but not by rhythm dependent indirect way. This direct pathway is not entirely caused by difference in eye structure.
In this study, we systematically studied the effects of light on subjective feelings from the aspects of time of day, lighting duration, monochromatic light wavelength, white light correlated color temperature and light intensity, and explored its mechanism. The results found that the effects of white light and monochromatic light on subjective perception were both affected by time, suggesting that the lighting duration and time- of-day must be taken into account in the future study and designing. In addition, our results showed that the subjective comfort were affected by light and eye structure together, which suggesting that individual differences should also be taken into account in the future. |
修改评论