The Washington Post

The less college students sleep, the worse their end-of-term grades, according to two-year study


The less a college student sleeps every night, the lower their end-of-term grade-point average will be, according to a two-year study of the sleep habits of more than 600 college freshmen that was published Feb. 13 in the journal PNAS.

Researcher­s found that every lost hour of average nightly sleep at the start of an academic term was associated with a 0.07-point drop in a student’s end-of-term GPA. When a student slept less than six hours a night, the effect on a student’s grades was even more pronounced, said David Creswell, the lead author of the study and a professor in psychology and neuroscien­ce at Carnegie Mellon University.

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.

The average student in the study fell asleep at about 2:30 a.m. Barely any of the students went to bed before midnight. And, on average, they slept 61/ hours a night.


Sleep recommenda­tions shift by age, and the amount of sleep an individual needs can vary. In general, for teenagers, the recommenda­tion is eight to 10 hours of sleep. For those ages 18 to 25, it drops to seven to nine hours.

Creswell and the team of researcher­s conducted five studies, recruiting college freshmen taking courses in a range of majors at Carnegie Mellon, the University of Notre Dame and the University of Washington. To monitor sleep, the students wore either a Fitbit Flex or a Fitbit HR for the entire academic term, a spring semester or a winter quarter, depending on the school, Creswell said.

After controllin­g for other factors — such as whether students take naps, their number of class credits and their GPA the previous term — the researcher­s found that average nightly sleep continued to predict a student’s end-ofterm GPA. What time a student went to bed and whether their bedtime varied day-to-day did not seem to play a role, Creswell said.

It’s unclear why less sleep would cause someone to have a lower GPA, Creswell said.

Sleeping for longer, uninterrup­ted periods of time allows for REM sleep, a period of unconsciou­s rapid eye movement that correspond­s with high activity in the brain.

Creswell said he suspects a regular pattern of insufficie­nt sleep creates a “sleep debt” over time, leaving students unable to concentrat­e.

Nightly sleep duration predicts grade-point average in the first year of college PNAS

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