Later High School Start Times May Benefit Teens' Mental Health

Starting high school 30 minutes later boosted adolescents' sleep, alertness, mood, and overall health, according to a study reported in the July Archives of Pediatrics and Adolescent Medicine.

The study, which involved more than 200 students in grades 9 through 12 at a private school in Rhode Island, extends research showing that adjusting school schedules to adolescents' circadian rhythms and sleep needs benefits students' mental and physical health.

Changes that occur in the biological clock at puberty make it hard for adolescents to fall asleep before 11 p.m., said Judith Owens, M.D., an associate professor of pediatrics at Brown University's Alpert Medical School, who directed the study.

Adolescents need 9 to 9.25 hours of sleep a night for optimal alertness, sleep laboratory studies show. Most high schools in this country start at 8 a.m. or earlier, however, requiring students to rise about 75 to 90 minutes before the opening bell. Nationwide surveys have found 80 percent of high school students get less than nine hours of sleep on school nights, said Owens, who directs the pediatric sleep disorders clinic and the learning, attention, and behavior clinic at Hasbro Children's Hospital in Providence, R.I.

According to the 2007 Youth Risk Behavior Survey of the Centers for Disease Control and Prevention, only 31 percent of U.S. students in grades 9 through 12 said they slept eight or more hours on school nights.

Chronic insufficient sleep undermines academic performance and boosts adolescents' risk of depressed mood and suicidal ideation, Owens said. It also contributes to drowsiness-related driving crashes, increased risk for weight gain and obesity, lack of exercise, and increased use of caffeine and other stimulants.

Owens supervised a two-month study of delaying the start time at St. George's School in Newport, R.I., from 8 a.m. to 8:30 a.m., in the 2009 winter term. By shortening a few periods, the school avoided changing the end of the school day, which was 3 p.m. on most days.

With parental permission, more than 200 of the co-ed school's 357 students completed a comprehensive eight-page questionnaire addressing sleep habits, sleep difficulties, moods, and behavior in the week before and after the schedule change. About 80 percent of the school's students were boarders, and the rest were day students. While the study was in progress, dormitory lights-out schedules for boarding students on school nights did not change. Students had no set wake-up time on Sunday.

With the later school start time, students in all grades slept 45 minutes longer on average on school nights. Mean sleep duration rose from 7 hours and 7 minutes to 7 hours and 52 minutes, more than researchers had anticipated. Some students reported they felt so much better with 30 minutes of extra sleep after the study began that they decided to go to bed earlier and sleep even longer. Before the change, only 16 percent of students reported sleeping at least eight hours a night; afterward, 55 percent did so. In both surveys, 12th graders slept about 40 minutes less than ninth graders.

The percentage of students who said they rarely or never got enough sleep fell from 69 percent to 34 percent. The percentage of those reporting they never felt satisfied with their sleep dropped from 37 percent to 9 percent.

The researchers found depressive symptoms overall were inversely correlated with reported sleep duration. The percentage of students who rated themselves as at least somewhat unhappy or depressed fell from 66 percent in the first survey to 45 percent in the second survey. “That's still quite worrisome,” Owens told Psychiatric News, adding, “It's unclear how much of this residual problematic mood is related to the still less-than-optimal sleep duration even after the time change.”

When school started later, students said they less often felt irritated or annoyed, or too tired to do schoolwork, play sports, or socialize. Fewer students made fatigue-related visits to the school Health Center. More ate hot foods at breakfast. Teachers reported a 45 percent drop in students who arrived late to or missed their first class.

After the trial ended, faculty and students voted overwhelmingly to retain the 8:30 a.m. start time, which continues today.

“Given growing evidence that delaying high school start times is good for adolescents, why aren't more schools changing to a later time?,” Kyla Wahlstrom, Ph.D., asked in an accompanying editorial.

Wahlstrom directs the University of Minnesota's Center for Applied Research and Educational Improvement. She led a multiyear assessment of effects of delayed high school start times on 50,000 students in the Minneapolis public schools. Results from the Rhode Island private school study echoed her findings.

“The time that school starts is like a community norm,” she noted. Although a call to delay opening time has sparked contentious debate in some communities, she said, “Our teenagers need and deserve our best-informed thinking about all of this.”

An abstract of “Impact of Delaying School Start Time on Adolescent Sleep, Mood, and Behavior” is posted at <http://archpedi.ama-assn.org/cgi/content/abstract/164/7/608>.