Morning Boost on Alertness, Cognitive Performance and Mood with Dynamic Lighting
Authors: Yanjie Li, Weining Fang, Beiyuan Guo, Haifeng Bao
Abstract: The monotonous lighting environment in the windowless workplace as well as the heavy tasks during peak hours can seriously affect healthy individuals’ vitality and work performance, with the result of leading to decision-making errors and even human safety accidents. In this study, an exploratory experiment on the perception of lighting environment was conducted in an experimental windowless environment, aiming at comparing the non-visual biological effects of static lighting and dynamic lighting on alertness, cognitive performance and mood during the peak morning work period. Meanwhile, the effect of task difficulty on lighting environment perception was also taken into account. All 16 subjects containing 8male and 8 female (mean age = 23.63 years, SD = 1.088 years) were required to perform a set of cognitive tasks under static light (4000K, 500lx) and dynamic light（CCT between 4000 and 12000K, 500lx）for 50 minutes. During each lighting condition, participants completed a 5-min Psychomotor Vigilance Task (PVT), an n-back task including 0-back, 1-back, 2-back, and a MATB-Ⅱ containing low, medium, high trials. Seven testing methods that questionnaires（Karolinska Sleepiness Scale, Positive and Negative Affect Schedule）, task performance（PVT, N-back, MATB-Ⅱ）and physiological methods（ERP, melatonin）were used to measure alertness, cognitive performance and subjective mood. The results indicated that a significant improvement in the subjective alertness and response speed to external stimuli under dynamic lighting vs. static lighting, which could depend on the duration of light exposure. N-back response time was significantly lower under dynamic lighting vs. static lighting and MATB-Ⅱ performance was also better under dynamic lighting which indicates that dynamic lighting has a significantly positive effect on individuals’ working memory and executive control function. Attention should be paid to the fact that the effect of dynamic lighting on cognitive performance was affected by the task difficulty. No significant difference was found between dynamic lighting and static lighting in P300, nor in the subjective mood. The findings from this study show the feasibility of dynamic lighting acting as an environmental intervention for supporting individuals’ psycho-biological wellbeing in a closed environment. Further study would concentrate on the non-image forming effects of dynamic lighting on alertness, cognitive performance and mood during the afternoon or night shift period.
Keywords: dynamic lighting, alertness, cognition, mood
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