A survey of 120 students at St. Lawrence University, a small liberal arts college in northern New York, found that students who have never pulled an all-nighter have average GPAs of 3.1, compared to 2.9 for those who have. The study, by assistant professor of psychology Pamela Thacher, is to be included in the January issue of Behavioral Sleep Medicine.
A second study by Thacher, a clinical psychologist, had "extremely similar" results showing lower grades among the sleep skippers.
Many college students, of course, have inadequate or irregular sleep, for reasons ranging from excessive caffeine to poor time management.
Dr. Howard Weiss, a physician at St. Peter's Sleep Center in Albany, said the study results make sense.
"Certainly that data is out there showing that short sleep duration absolutely interferes with concentration, interferes with performance on objective testing," he said.
Some night owls do get good grades, of course, which may be explained by circadian rhythms, Weiss said. Circadian rhythms can be tracked through body temperature and hormonal transmissions.
Some people have different 24-hour body clocks than others, and may do better depending on class and testing times, Weiss said.