By Amanda Gardner

HealthDay Reporter

MONDAY, July 5 (HealthDay News) -- High school students at a private school in Rhode Island who started school a half-hour later in the morning were in better moods, more alert, less depressed and more likely to actually attend class than before the time change, a new study shows.

In fact, the experiment was so successful that the school has now permanently shifted its start time from 8 a.m. to 8:30 a.m.

"At the end of the experimental period, there was not a single faculty member, student or administrator who wanted to go back to the old start time," said Dr. Judith Owens, lead author of a paper appearing in the July issue of the Archives of Pediatrics & Adolescent Medicine.

"Mornings are so much more pleasant at my house I can't even begin to tell you," added Owens, whose daughter just graduated from the school and who participated in the experiment. "Many of the faculty members said the same thing: that it improved the quality of their lives as well as the perception that students were just better rested and more ready to start the day."

The study bolsters the evidence that teens have special sleep needs.

"Sleep medicine specialists have long known that delaying high school start times helps teenagers sleep better," said Dr. Heidi V. Connolly, chief of the division of pediatric sleep medicine at the University of Rochester Medical Center in New York. "Teenagers are biologically programmed to prefer a later bedtime and a later wake-up time so it is not surprising that they struggle with early school start times."

Adolescents' circadian rhythms do shift during puberty. "What that boils down to is that teenagers are not able to fall asleep as early as they did when they were in middle school or elementary school," Owens explained. "There is as much as a two-hour shift in sleep-wake cycles."

But while they may be going to bed later, they still need the same amount of sleep, making sleep deprivation "rampant among American teens," Connolly said.

Owens was approached by St. George's School in Middletown, R.I., about doing a study on a later school start time.

"There was a lot of push back initially from faculty, administration and athletic coaches who felt that half an hour wasn't going to make a substantial difference and was going to be disruptive to academic and athletic schedules," Owens said.

But they agreed to give it the old college try.

About 200 students in grades 9 through 12 filled out questionnaires on sleep habits both before and after the time change. The researchers also measured tardiness and visits to the school health center.

After the time change, students went to bed an average of 18 minutes later at night and slept an average of 45 minutes longer.

The proportion of students getting at least eight hours of sleep a night jumped from 16.4 percent to 54.7 percent, while those getting less than seven hours a night decreased by almost 80 percent.

Other parameters improved as well.

"Virtually everything we looked at -- ranging from the amount of sleep to self-reported sleepiness during the day, to mood and depression symptoms, to interest and motivation to participate in academic and athletic activities -- moved significantly in a positive direction," Owens stated.

As noted in an accompanying journal editorial, research into this topic started in Minnesota 13 years ago and resulted in the Minneapolis Public School District changing the start time of high schools to 8:40 a.m. and of middle schools to 9:10 a.m.

But there's still a lot of resistance to the idea, with some school superintendents actually losing their jobs after supporting the idea of later school times, wrote editorialist Kyla Wahlstrom, of the University of Minnesota.

And even with this new evidence, it's not clear if such changes would work at all schools or if the dramatic improvements seen here would even last.

"It might just be the teenagers were going to bed the same time and got an extra 30 minutes of sleep which was beneficial," said Dr. Lawrence Friedman, director of the adolescent medicine program at the University of Miami Miller School of Medicine. "But will [a later school start] translate to teenagers wanting to stay up another half hour? If so, then it would cancel out the benefit."

More information

There's more on adolescent sleep needs at the National Sleep Foundation.