Study finds correlation between grades and lack of sleep
Matthew Broder | Wednesday, February 22, 2023
Late night studying might be doing students more harm than good, according to a recent study involving the work of Notre Dame researchers.
The study, published in the Proceedings of the National Academy of Science, found an association between average hours of sleep a night and a student’s GPA. For every average hour of nightly sleep lost over the semester, students’ GPAs dropped by 0.07 points.
The study measured the sleeping habits of first-year students at three universities, including Notre Dame, over the course of a semester. Lower average nightly sleep throughout the term predicted lower GPAs by the end of the semester, even when controlling for factors like course load and previous-term GPA.
A Washington Post piece about the study pointed out that “Sleep, especially undisturbed sleep, helps the brain process and retain information it has learned. And when someone is sleep-deprived, attention span and memory also are impaired.”
Sleep has long been known to be an important part of the learning process. But this study provides quantifiable data to prove it, especially in the case of young adults.
The National Sleep Foundation recommends that young adults get seven to nine hours of sleep per night. Yet in this study, first-year college students across all five samples slept, on average, only around six and a half hours per night. Around 20% slept less than six hours, and only around 5% got more than eight hours. The numbers are striking, but they make sense.
“While these patterns of insufficient sleep may be troubling, they have also been found across other collegiate student samples,” the authors wrote in the study. The exact reasons behind why less sleep would cause someone to have a lower GPA are unclear, but Stephen Mattingly, a postdoctoral researcher here at Notre Dame who was involved in the study, offered a few possible explanations.
“Adequate sleep is a really exceptional way for the brain to store new information and to sort it in ways that are useful for future use,” he said. “Specifically, during sleep, important parts of memory are replayed and ‘transferred’ into what we already know. In addition, there is global synaptic downscaling, which ‘resets’ the brain and the relative strength of neurons, especially for unremarkable or boring things.”
Because of the crucial role sleep plays in memory consolidation, it would make sense that sleep has a direct effect on academic performance. More sleep would help integrate concepts learned more efficiently and make memories that last longer, both of which are helpful on exams and finals.
“Not sleeping enough also degrades your ability to learn new information in the first place and serves as a physiological stressor,” Mattingly said. “[It] can make it hard to access information you already know, which can be critical for test-taking that underpins much of grade determinations.”
David Hachen, a fellow researcher here at Notre Dame who was also involved in the study, concurred with Mattingly.
“It may be better to think about what people gain when they get more sleep. Sleep has a cleansing and rejuvenating effect on our brains,” he said.
The study also gave context to the importance of sleep in college students beyond the potential adverse effects on GPA. College is a major life transition between childhood and adulthood, and sleep means more than ever.
“First-year college students are making some of their first efforts to establish independent sleep habits, often doing so amidst new competing pressures of work and dorm life activities and a challenging academic course load,” the authors wrote. These habits that first-year students form will stick with them even after college, and sleep debt will continue to build up unless there is some sort of intervention.
Mattingly offered advice to students struggling with finding the time for sleep.
“Sleep is a powerful study tool,” he said, “[Students should] consider it on a similar tier to physical exercise and nutrition. Further, sleep is critical to mental, emotional and physical health. Sometimes, sleep can be a way to work smarter rather than working harder.”