Excessive daily reading is linked to lower academic test scores among Japanese students, according to an analysis of nationwide testing data [1].
This finding challenges the common assumption that more reading always leads to better academic outcomes. By identifying a specific threshold where benefits decline, the data provides new insights for educators and parents regarding balanced study habits.
The Ministry of Education, Culture, Sports, Science and Technology conducted the national academic achievement tests among approximately 2 million students in the sixth grade of elementary school and third year of junior high school [1]. The analysis focused on the relationship between reading habits and test results, specifically looking at data from the spring of 2026 and reading time data from the 2026 and 2026 academic years [2].
Researchers identified a "reverse-U phenomenon" in the data. While moderate reading contributes to higher scores, reading for more than two hours per day is associated with a decrease in the correct answer rate [2]. This pattern was consistently observed across both the 2026 and 2026 data sets [2].
Other findings from the broader survey indicated a gender gap in performance, with girls achieving higher correct answer rates in the Japanese language section than boys [3]. The Ministry said the goal of the research was to clarify the relationship between reading habits and academic ability to inform future education policy, and home learning guidance [3].
Recent efforts to monitor these trends continued with the implementation of the 2026 academic achievement and learning status survey [1].
“Reading for more than two hours per day is associated with a decrease in the correct answer rate.”
The discovery of a 'reverse-U' relationship suggests that academic success is not linearly tied to the volume of reading. This implies a point of diminishing returns where excessive reading may displace other critical learning activities, such as sleep, physical exercise, or targeted study of other subjects. For policymakers, this shifts the focus from simply encouraging 'more' reading to promoting a balanced approach to literacy and time management.
