College students who regularly cram all-night for exams and papers get lower grades than students who don't, according to a new study out of St. Lawrence University in Canton, NY.  

Psychology professor Pamela Thacher studied the sleep habits and academic transcripts of 111 students and found that two-thirds reported pulling at least one all-nighter a semester. Those that did it regularly also had lower grade-point averages, she found.

Thatcher's findings will be published in the January issue of the journal Behavioral Sleep Medicine.

The conventional wisdom is that all-nights are associated with procrastination -- another venerable college tradition -- but Thatcher did not find a correlation.

"The data indicate that procrastination is not associated with all-nighters, although both practices significantly correlated with lower GPAs," she said in a university news release.