Schools could see their maths scores rise if they schedule lessons in the morning, research suggests.
But youngsters do better in history if they have classes in the subject after lunch.
The study, by an academic at Royal Holloway, University of London looked at academic achievement, class schedules and absence rates at a Bulgarian school over nine years.
The findings, to be presented at Britain's Royal Economic Society conference, show that when teenagers had maths classes earlier in the day, they did better than if they had the same class in the afternoon.
For history, the opposite was true.
"The findings indicate that afternoon classes lowered maths test scores and increased history test scores, which relate to psychology and neuroscience research about optimal functioning in different times of the day," the study concludes.
It indicates that by rearranging timetables, schools can improve students' results, author Velichka Dimitrova says.
The findings back up psychology research that has found it is better to perform repetitive tasks earlier in the day, while tasks that involve making sense of something are better done later on, it was suggested.
