It’s common for teenagers to stay up late cramming on the night before a test or quiz, but a study from University of California, Los Angeles, suggests the lost hours of shut-eye counteract the benefits of extra studying.
Researchers in the study, published in the August issue of Child Development, asked 535 students to keep daily diaries on their sleep and study habits for 14 days in the 9th, 10th and 12th grades. While students’ study time did not change much throughout high school—they studied about an hour a night on average—students got progressively less sleep over time. In part, that was because students were more likely to sacrifice sleep than other activities to find time to study.
But no matter how much time a student studied, if sleep was sacrificed to do so, the student had more difficulty the following day understanding new material and was more likely to perform poorly on a test or task.
