Optimal sleep duration varies by subject: about 8–9 hours for mathematics and 7–8 hours for Chinese, English, science, and arts¶

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? Quadratic regression vertex estimates place the optimal sleep interval at 8–9 h for mathematics and 7–8 h for the other subjects. → 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

Quadratic OLS vertex calculation (−b/2a) on sleep treated as an ordinal variable (1 = <6 h to 6 = >10 h), yielding subject-specific turning points from the regression coefficients in Table 2.

"The results suggest that for Chinese, English, science, and the arts, the o p t i m a ld u r a t i o ni sa p p r o x i m a t e l yb e t w e e n7a n d8 h ,w h i l ef o rm a t h e- matics, it lies between 8 and 9 h."

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 — 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
• Sleep duration shows an inverted U-shaped association with academic performance in all five subjects, with a peak around 8 hours of nightly sleep — a broader claim this one bears on
• Threshold regression corroborates the inverted U: performance gains below 7–9 h and significantly negative coefficients beyond the second threshold — related
• The positive association between sleep and performance is strongest among lower-achieving students — related
• 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
• Only 22.34% of Chinese school-aged children get sufficient sleep (≥10 hours), while 37.96% have short sleep duration (<9 hours) — related