To Study or to Sleep? The Academic Costs of Extra Studying at the Expense of Sleep


  • Support for this study was provided by a grant from the Russell Sage Foundation. We are extremely grateful to the principals and teachers who welcomed us into their schools and to the students who shared their daily lives with us.

  • [Correction added on 9/7/2012, after first online publication 8/20/2012: Virginia W. Huynh’s affiliation has been corrected to California State University, Northridge.]

concerning this article should be addressed to Cari Gillen-O’Neel, Department of Psychology, University of California, 1285 Franz Hall, Los Angeles, CA 90095-1563. Electronic mail may be sent to


This longitudinal study examined how nightly variations in adolescents’ study and sleep time are associated with academic problems on the following day. Participants (= 535, 9th grade Mage = 14.88) completed daily diaries every day for 14 days in 9th, 10th, and 12th grades. Results suggest that regardless of how much a student generally studies each day, if that student sacrifices sleep time to study more than usual, he or she will have more trouble understanding material taught in class and be more likely to struggle on an assignment or test the following day. Because students are increasingly likely to sacrifice sleep time for studying in the latter years of high school, this negative dynamic becomes increasingly prevalent over time.