Results from high school senior sleep/wake diaries kept for the study also showed that adolescents lost as much as two hours of sleep per night during the school week, but weekend sleep times during the school year were similar to those in summer.
The study was a collaborative project involving researchers at the Feinberg School of Medicine and the Center for Sleep and Circadian Biology at Northwestern University and faculty, students and parents from Evanston Township High School, Evanston, Ill. The students were advanced placement biology students who helped conduct the study and analyze the collected data.
Martha Hansen, advanced placement biology teacher and current science department chair at Evanston Township High School, headed the project in collaboration with Margarita L. Dubocovich, professor of molecular pharmacology and biological chemistry and of psychiatry and behavioral sciences, Feinberg; and Phyllis C. Zee, M.D., professor of neurology, Feinberg.
The study assessed the impact of sleep loss after the start of school on cognitive performance and mood and examined the relationship of weekday to weekend sleep in adolescents.
The study also showed that exposure to bright light in the morning did not modify students' sleep-wake cycle or improve daytime performance during weekdays probably because of their strict school schedule. All students performed better in the afternoon than in the morning. Students in early morning classes reported being wearier, less alert and having to expend greater effort. Potential solutions to this problem could be solved by changing school start times and by giving standardized tests later in the day, the authors suggested.