High school students who choose to sacrifice their sleep to get extra studying time in may fare worse academically the next day compared with their well-rested peers, new research suggests.
In a study released Tuesday in the journal Child Development, UCLA researchers studied 535 students as they progressed through ninth, 10th and 12th grade to see how lack of sleep affected their academic performance. Using a diary that they kept for 14 days straight, the students answered the following questions:
Did you do homework or study today while not in school? If yes, for how long?
How many hours and minutes did you sleep last night?
Did you have problems understanding something taught in class today or do poorly on a test, quiz, or homework?
What researchers found was that as the students advanced through high school the downsides of sacrificing sleep time for study time became more apparent. Ninth grade students who spent extra time studying on a particular night did not have worse academic performance the next day. By 12th grade, however, students who made the same tradeoff reported deficits the next day in understanding class material or on test performance.
In practical terms, this study argues that studying at the expense of sleep may not be a wise decision.
"Although studying is essential, sleep is important for learning," says Dr. Phyllis C. Zee, professor of neurology and director of the Sleep Disorders Center at Northwestern University. "Even one night of sleep loss can negatively affect performance.
"This should make not only high school students but also college students and even professionals rethink the common practice of 'cramming' for exams, work projects, et cetera, at the expense of sleep loss."
Other experts agree that high schoolers, known to have poor sleep habits to begin with, are in particular danger of cramming in lieu of sleep.
"Cramming does not work at the higher levels of high school," says Rosalind Cartwright, professor and chairman of the department of psychology at Rush University. "It shortens sleep in a population which is already known not to get enough sleep."
This may be happening to students who need sleep the most. Some experts suggest that cramming may not be causing poor performance but rather, poor performers may be the ones cramming.
"It is equally possible that the extra study is the result of the student knowing they have a problem with material that shows up on the test," explains Dr. David Rapoport, associate professor of medicine and director of the sleep medicine program at NYU School of Medicine.
Dr. Andrew Fuligni, professor of psychiatry at UCLA and senior author on the study, emphasizes that it is not problematic to spend more time studying overall -- as long as it is not at the expense of sleep. Previous studies have confirmed that the same amount of study time spread evenly over several days leads to better academic performance than trying to study all at once.
He makes several recommendations for adolescents, including using their school time efficiently, including study hall or between classes, and spending less time on outside activities.
"On average, adolescents spend about an hour each day socializing with friends, about an hour each day helping the family, and between one and two hours each day watching television," he says, adding that many even fit in extracurricular activities and paid work. Part of the solution, he suggests, may lie in spending less time on these outside activities.
Other sleep experts agree. "Time management skills are important to foster in teens," says Dr. Stacia Sailer, director of the UMass Memorial Sleep Disorders Center.
But what would experts recommend for busy teens that cannot have a regular study schedule?
"I advise students if they need to cram, they should do it a day ahead so that they ensure they can get a good night's sleep before the exam," says Joyce Walsleben, associate professor of medicine at NYU School of Medicine.