# A Study on the Impact of Blue Light and Its Brightness on Long-Term Memory
## 3 Result and Discussion
### Discussion  
In conclusion, the major findings of this study have significance, as detailed below. First, the present study experimentally verified the hypothesis that blue light is more effective in facilitating long-term memory retrieval compared to red light as a comparison group. In all tests, memory retrieval was higher under blue light than under red light, regardless of light brightness. These findings are consistent with previous studies that have highlighted the significant contribution of blue light to enhancing cognitive abilities, including attention, working memory, and long-term memory [19; 20; 21]. Second, this study confirmed that the effect of light on long-term memory enhancement increases with its brightness. This relationship was observed both in blue light and red light, regardless of light color. However, these results contradict the findings of previous studies reporting higher long-term memory retention under light with an illuminance of 400 lux compared to 1000 lux [11; 12; 13]. For instance, [PERSON] et al. (2017) concluded that long-term memory retention was the highest when illuminance was 400 lux compared to 700 and 1000 lux [13]. However, it is worth noting that these contradicting results were obtained using white light lighting sources rather than blue or red light. These mixed findings suggest that the optimal light brightness for long-term memory retention may vary depending on its color. Future studies should focus on the comparison of long-term memory enhancement between white light and blue light. Further experimental evidence is required to conclude that blue light is more effective than white light in enhancing long-term memory. Meanwhile, in this study, the highest illuminance was set to 1000 lux; however, there is no guarantee that even brighter light is more effective in long-term memory enhancement. All these questions should be addressed through further research. Finally, there was no evidence for the interaction effect between light brightness and color. Despite being statistically insignificant, however, the difference in the contribution of red light and blue light to long-term memory enhancement gradually narrowed as their brightness increased, as indicated in Figure 2. This indicates that it is even possible to compensate for the effect of light color by increasing the brightness further. Additionally, it is still necessary to determine the optimal light environment as it influences the contribution of blue light to long-term memory enhancement. What is the optimum brightness of blue light to maximize long-term memory retention? How does the effect of light color vary as its  
Figure 4: Differences in long-term memory according to blue light and brightness of light. brightness increases? These questions should be further addressed to gain a comprehensive understanding of the overall effect of light on memory. Hence, future studies should focus on these aspects. Despite its significance and originality, this study still has limitations that need to be addressed. First, this study's participants were predominantly young men and women in their twenties. However, the elderly, rather than young people, are more prone to difficulties associated with memory. That said, it is challenging to recruit the elderly for this type of experiment in practical settings. Moreover, given the situation, the total number of participants was relatively small at 25. Therefore, caution should be exercised in the generalization of the findings of this study to all age groups. Future studies will address these limitations by including more extensive age groups, increasing both sample diversity and size. Second, the dark (400 lux) and bright (1000 lux) light conditions employed in this study were set with reference to previous studies on long-term memory, but these specific brightness levels do not universally represent what is typically considered a \"dark\" or \"bright\" light environment.