Sleep duration shows an inverted U-shaped association with academic performance in all five subjects, with a peak around 8 hours of nightly sleep¶

Claim · All claims
Evidence · 1 study · associational r2 · q2
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? Sleep duration is positively associated with achievement in all subjects while its squared term is negative, indicating an inverted U-shaped relationship in OLS regression. → Wang 2025

Evidence¶

Wang 2025¶

Wang, M., Chen, Z., Han, N., & Yao, H. (2025). Sleep duration and subject-specific academic performance among adolescents in China. npj Science of Learning. https://doi.org/10.1038/s41539-025-00361-y

q2 · i? · associational · r2

OLS regression on the observational dataset of Shanghai eighth-graders who provided both sleep and performance data (valid sample 54,102), across Chinese, math, English, science and art. The article reports "the squared term of sleep duration is significantly negative (p < 0.001)" for all subjects.

"sleep duration is significantly and positively associated with academic achievement in all sub- jects (p < 0.001), while the squared term of sleep duration is significantly negative (p < 0.001), indicating an inverted U-shaped relationship"

Discussion¶

Learner Variables¶

• Sleep — predictor: learners who differ on it differ in outcomes

Related Claims¶

• Gender differences in optimal sleep duration: girls need slightly longer sleep than boys in most subjects, except mathematics — a narrower finding that bears on this claim
• Each additional hour of homework is associated with about 0.335 fewer hours of nightly sleep, and electronic device use is also negatively associated — related
• Short sleep duration (<9 hours) at follow-up is associated with impaired academic achievement, while baseline sleep duration did not significantly predict later school performance — related
• Threshold regression corroborates the inverted U: performance gains below 7–9 h and significantly negative coefficients beyond the second threshold — related
• Sleep duration contributes more to variance in Chinese, mathematics, and science performance than to English and arts, but less than socioeconomic status in every subject — related
• Optimal sleep duration varies by subject: about 8–9 hours for mathematics and 7–8 hours for Chinese, English, science, and arts — a narrower finding that bears on this claim