A summary of what researchers know about teenagers' need for sleep and how sleep affects memory and learning, by FRONTLINE producer Sarah Spinks.

Carskadon is a professor of psychiatry and human behavior at Brown University and director of chronobiology and sleep research at E.P. Bradley Hospital in Providence, R.I. Her research focuses on the interrelation between the circadian timing system and sleep/wake patterns of children and adolescents. Her work has highlighted the consequences of insufficient sleep in adolescents, as well as concerns about early school starting times.

Smith is a professor of psychology at Trent University in Peterborough, Ontario. His research focuses on increasing understanding of how the brain, during sleep, continues to process information that was learned while awake. In this interview with FRONTLINE, Smith recounts the human and animal studies that suggest a good night's sleep helps reinforce the cognitive and motor tasks learned during the day.

Published by the National Sleep Foundation's Sleep and Teens Task Force, this report is divided into two sections: a research report that consolidates current research on the physiological, behavioral, and psychosocial patterns of poor sleep in adolescents, and a resource guide for parents and teens with tips on how to improve their sleep habits. The resource guide also provides a summary of findings from high schools that have later start times, and a fact sheet on "drowsy driving."

Published in the Nov. 2, 2001, issue of Science, this article by Jerome M. Siegel of UCLA's Department of Psychiatry and Brain Research Institute, suggests sleep may be less important to learning than researchers had previously believed. Siegel argues, "Although sleep is clearly important for optimum acquisition and performance of learned tasks, a major role in memory consolidation is unproven."

The Center for Applied Research and Educational Improvement at the University of Minnesota has done several studies of Minnesota school districts regarding changes to later start times for high schools. Published in November 1998, its comprehensive first study examined 17 districts in the Minneapolis-St. Paul area to find out the various costs to the school and community. The study surveyed students, teachers, parents, administrators, community members, and medical researchers. Researchers also spoke with many other constituencies that would be affected by the change, including those involved with transportation, athletics, fine arts, community education, food service, and juvenile crime, as well as student employers.

The second study, released in August 2001, examined data regarding student grades and attendance in the Minneapolis School District. It found that attendance in the district had improved significantly from 1995-2000, but that although there was a slight improvement in grades earned overall, the difference was not statistically significant. However, the study also cautioned, "A finding from this time-consuming and intensive data analysis is that the difficulty of making comparisons and subsequent judgments is likely to be a problem for any district attempting to judge the efficacy of a change using letter grades earned as the primary indicator."