Effect of LED Lighting Illuminance and Correlated Color Temperature on Working Memory

Abstract

This study was conducted to verify how the illuminance and correlated color temperature of LED lighting affect working memory. For this study, an automatic LED lighting device based on a light sensor was developed and used, and the lighting conditions were treated with a total of six conditions (2 × 3): two illuminance conditions (dim: 400 lx, bright: 1,000 lx) and three correlated color temperature conditions (3,000 K, 5,000 K, and 7,000 K). There were 30 participants in the study, and the average age was 21.6 years (Standard deviation = 1.92). Participants were assigned to all six lighting conditions, and the placement order was randomized. For the measurement of working memory, 3-back task was used and the correct responses for 5 minutes were used as a dependent variable. As a result of repeated measures analysis of variance (ANOVA), both illuminance and correlated color temperature were found to be significant variables affecting working memory, and no interaction effect between illuminance and correlated color temperature was found. As a result of the post hoc verification conducted thereafter, the working memory performance in the bright light condition (1,000 lx) was 48.32 (Standard deviation = 15.63) on average, compared to 44.80 (Standard deviation = 15.29) in the relatively dim condition (400 lx). It was found that the condition of bright light was superior in performing working memory compared to relatively dim condition. The working memory performance in the correlated color temperature condition (5,000 K) was 48.32 (Standard deviation = 16.41) on average and higher than that of other color temperature conditions. As a result, working memory performance was the best in 1,000 lx, 5,000 K condition Mean = 53.43 (Standard deviation = 18.38), and 400 lx, 7,000 K condition Mean = 42.73 (Standard deviation = 17.68) showed the worst performance of working memory.

Determination and Measurement of Melanopic Equivalent Daylight (D65) Illuminance (Medi) In the Context of Smart and Integrative Lighting

“…Parameter Preferred values Horizontal illuminance E v,h in lux [12][13][14] Greater than 850 lx; Recommended range: 1300 lx -1500 lx Correlated color temperature CCT in K [15,16] 4000 K -5000 K Color rendering index CIE CRI [10] > 80 Indirect to total illuminance ratio γ [11,17] > 0.6 -0.8 In recent years, there has been a large amount of research and publications on non-46 visual lighting effects analyzed and reviewed in books and literature reviews [18][19][20][21]. In the majority of scientific publications cited in these reviews, the input parameters de-48 scribing lighting conditions were photometric metrics (illuminance, luminance) and/or 49 color temperature.…”

Effects of indoor lighting environments on paper reading efficiency and brain fatigue: an experimental study

“…In lighting conditions of 500 lux and 5000K, attention and work efficiency are at their highest with fatigue at its lowest (Yu and Akita, 2023). Under 1,000 lux and 5000 K conditions, individuals display optimal working memory performance but perform less effectively under conditions of 400 lux and 7000 K (Lee and Kim, 2020).…”

Determination and Measurement of Melanopic Equivalent Daylight (D65) Illuminance (mEDI) in the Context of Smart and Integrative Lighting

“…As a result of this research process, international and national standards (e.g., EN 12464 standard [9]) have been formulated for lighting design and the development of interior lighting systems. For special applications (e.g., exhibitions, meeting rooms in prestigious buildings, and treatment rooms in medical centers and hospitals) the following values in Table 1 [10][11][12][13][14][15][16][17] from research studies have been used. Table 1.…”