How exam timing affects school performance differently in early and late daily types

In a study of 741 Dutch high school students, very late chronotypes or those who sleep less than 7.03 hours on schooldays received the lowest grades.

• Chronotype correlates with examination performance, particularly among adolescents.
• Students classified as very late chronotypes (MSFsc > 5.31 h) consistently perform worse academically.
• Early chronotypes achieve significantly higher grades during morning examinations compared to late chronotypes.
• The performance gap between early and late types diminishes in the early afternoon.
• Late chronotypes show lower grades even when tested at the same internal time, indicating potential attention and learning challenges.

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