Teenagers who go to bed earlier and sleep for longer than their peers tend to have sharper mental skills and score better on cognitive tests, researchers have said. They expected teenagers with healthy sleeping habits to score better than those who slept poorly but were surprised at the impact that even small differences in sleep made.

A study of more than 3,000 adolescents showed that those who turned in earliest, slept the longest, and had the lowest sleeping heart rates outperformed others on reading, vocabulary, problem solving and other mental tests.

A good night’s rest has long been linked to better mental performance, but researchers are still teasing apart what happens in adolescence when crucial brain development coincides with a shift towards later bedtimes and less sleep overall.