Morningness–Eveningness and Intelligence among High-Achieving US Students
This study examined whether chronotype (morningness vs. eveningness) is associated with cognitive ability among high-achieving individuals, specifically MBA students at a top-ranked U.S. business school. Previous research had found small but consistent links between eveningness and higher intelligence in general populations; this study tested whether the relationship persists at the upper end of academic and intellectual ability
A total of 201 MBA students at the University of Chicago reported whether they identified as night owls or early-morning types, provided information on sleep duration, and had their GMAT scores, undergraduate GPA, and graduate GPA analyzed. Baseline salivary cortisol levels were also measured to explore whether physiological arousal explained any chronotype-related differences in performance
The results showed that night owls scored significantly higher on the GMAT than early-morning types, regardless of sex. Men also scored higher than women on average, but there was no interaction between sex and chronotype, indicating that the night-owl advantage applied similarly to both men and women. Significantly, chronotype was not related to undergraduate GPA, graduate GPA, or sleep duration, suggesting that higher GMAT scores among night owls were not due to differences in study effort or amount of sleep
A regression analysis revealed that sex, chronotype, and baseline cortisol together explained about 14% of the variance in GMAT scores. Although higher cortisol levels were weakly associated with higher GMAT scores, cortisol did not mediate the relationship between chronotype and GMAT performance. Thus, physiological stress levels could not explain why night owls performed better
Overall, the study concludes that the relationship between eveningness and higher cognitive performance exists even among elite, high-performing students. While the effect size is modest, the findings suggest that chronotype-related differences in intelligence are not simply artifacts of sleep habits or academic effort, but may instead reflect stable cognitive or personality differences. The authors note limitations such as the elite sample and use of a single-item chronotype measure, and they emphasize the need for further research into the psychological and neurobiological mechanisms underlying chronotype differences
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