A University of Kentucky study published in a medical journal shows that when Fayette County schools moved their high school start times back by an hour in 1998, it markedly improved students' sleep habits and might have helped reduce teen car accidents.
The study, published in the most recent Journal of Clinical Sleep Medicine, relied on survey results from about 10,000 Fayette County middle and high school students in 1998 and 1999. Ninth-graders averaged 12 minutes more sleep a night, and seniors said they got an average of an extra half-hour of sleep after the school system moved back the start times.
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Between the 1997-98 and 1998-99 academic years, Fayette County Public Schools moved high school start times from 7:30 a.m. to 8:30 a.m. Currently, the five Fayette County public high schools begin their days at 8:25 a.m.
"The percentage of students who got at least 8 hours of sleep per weeknight increased significantly, from 35.7 percent to 50.0 percent, and the percentage who got at least 9 hours of sleep increased significantly, from 6.3 percent to 10.8 percent," said the journal article, written by UK's Dr. Barbara Phillips and Fred Danner.
The study also showed the students needed less catch-up sleep on the weekends.
Phillips, professor of pulmonary critical care and sleep medicine in UK's internal medicine department, and Danner, UK's educational psychology department chairman, also found that the rate of car crashes involving teenagers in Fayette County decreased 16.5 percent in the two years after the start-time change, while it increased 7.8 percent in Kentucky in that time.
The professors noted in their article that the study didn't take into effect other related factors, such as number of miles driven by the teenagers in that time frame, but they said there seemed to be a strong correlation.
"These data are consistent with the idea that allowing adolescents to sleep more on school nights by delaying the start of school not only results in them sleeping more, but also may have a measurable positive effect on their driving safety," Phillips and Danner wrote.
Lisa Deffendall, spokeswoman for Fayette County Public Schools, said the school system is aware of the study's results and "there is no discussion about making any changes in our start times in the district."