Too Little, Too Late
East Providence, R.I.
A Brown University sleep researcher has some advice for people who run high schools: Don't start classes so early in the morning. It may not be that the students who have nodded off at their desks are lazy. And it may not be that their parents have failed to enforce bedtime. Instead, it may be that biologically these sleepyhead students simply can't handle the early hour.
"These kids may be being asked to function at the wrong time for their bodies," says Mary A. Carskadon, a professor of psychiatry and human behavior at Brown's school of medicine.
Carskadon, who is considered the pre-eminent researcher looking at behavioral, psychological, and other aspects of adolescent sleep, is trying to understand more about the effects of early school schedules on teenagers. And, at a more basic level, she and her colleagues are trying to learn more about how the biological changes of puberty affect sleep needs and patterns.
Carskadon, who is also the director of chronobiology and of the sleep research laboratory at E.P. Bradley Hospital here, says her work suggests that teenagers may need more sleep than they did before puberty, not less, as commonly thought.
Sleep patterns change during adolescence, as any parent of a teenager can testify. Most adolescents prefer to stay up later at night and sleep later in the morning. But it's not just a matter of choice--their bodies are going through what researchers call a "delayed phase preference."
All of this makes the transition from middle school to high school--which may start one hour earlier in the morning--all the more troublesome, Carskadon says. With their increased need for sleep and their internal clocks set on "sleep late, rise late" mode, adolescents are up against a double whammy when it comes to trying to be up by 5 or 6 a.m. for a 7:30 a.m. first bell. A nap, be it on a desktop or wherever, may be their body's way of saying, "I need a timeout."
To hear Carskadon and her colleagues talk about it, sleep seems to be the Rodney Dangerfield of human biology: It doesn't get any respect. They say the importance of sleep is too often overlooked. That is odd, they think, for an activity that consumes some one-third of our lives.
"There's no concept that sleep plays an important role," Carskadon says. "It's the last thing people think about."
Indeed, sleep isn't even mentioned in the Carnegie Corporation's otherwise comprehensive book on adolescent development, At the Threshold: The Developing Adolescent.
People need to think of sleep as "one of the fundamental foundations for good health," Carskadon argues. "It helps to set the clock, helps to give synchrony to the day."
Amy R. Wolfson, an assistant professor of psychology at the College of the Holy Cross in Worcester, Mass., has been working with Carskadon on the study of students making the transition from 9th to 10th grade. Early results from the small group of 15 students studied last year show that the teenagers were getting significantly less sleep in 10th grade than they did the year before. As 9th graders in junior high, the students' day began at 8:25 a.m. As 10th graders starting high school, they had to be at school at 7:20.
According to the study, which has continued with another group this year, these high school students weren't staying up later. In fact, they were going to sleep at about the same time as before. But the sleep deficit caused by having to get up earlier puts them at significant risk of schooltime sleepiness. And that means not only are students missing out on classroom lessons, but they may be at risk of nodding off behind the wheel of a car.
During the study, students who were keeping their regular weekday schedules were given nap tests to test for "sleep latency." They were asked several times during a day to close their eyes and try to fall asleep. The researchers gave them about 15 or 20 minutes to fall asleep and timed the students to see how long it would take them to do so.
It turns out, Wolfson says, it didn't take long. On average, it took the 9th graders just 9.5 minutes to fall asleep. When they began 10th grade, they were snoozing in an average 8.4 minutes. The sleepiest 9th grader took 5.1 minutes to fall asleep, while the most tired 10th grader was able to nod off in as little as 1.8 minutes.
All together, four of the 10th-grade students were able to fall asleep in less than five minutes. And, in a finding that still impresses the researchers, one of those went right into rem sleep, usually the last stage of sleep. Someone who falls into rem sleep that easily is sleep-deprived, Wolfson says.
The researchers say younger children tend not to fall asleep when they are given such a chance. But the difference is these students were all well into puberty. The teenagers' bodies, they say, were desperately trying to make up for a sleep deficit.
Regardless of their age, "People shouldn't be falling asleep so quickly like that during the day," Wolfson says. "These kids are likely to be the ones falling asleep in class."
Natalie Burrows was one of the students who participated in last year's school-transition study. Natalie, who started the 11th grade at East Providence High School this fall, knows how hard it was to go from her 9th-grade schedule to her 10th-grade schedule. She has always been a night person, even as a young child. In junior high, she couldn't go to sleep before 1 a.m. or 2 a.m.
Then, the high school change came. In junior high, she had to be at school by 8 a.m. In senior high, that moved up to 7:15 a.m. "The fact that I stayed up late had more of an effect because I had to get up earlier--the first hours of school I'd be dead," she recalls. "Going toward lunchtime I was fine. It was just that first hour-and-a-half that was terrible."
Cluing In to Biology
Carskadon has made researching adolescent sleep the centerpiece of her 25-year career. But a turning point of sorts came for her and her team when they analyzed the results of a study of 6th-grade students and their sleeping and waking patterns and preferences. That's when they uncovered their first real indication that biology--specifically puberty--could explain the delayed-phase preference among adolescents.
The January 1991 teachers' issue of SuperScience Blue, a science magazine for 4th though 6th graders published by Scholastic Inc., carried a letter from Carskadon asking for teachers who would be willing to have their students participate in a research project. Thirty-six schools with 6th graders took part. The researchers targeted 6th graders because they wanted students who would be close in age and psychosocial experiences but would also span several stages of puberty. The study group numbered 183 boys and 275 girls.
The youngsters responded to questionnaires that asked about everything from what bedtime they would pick if their parents let them choose to what time of day they have the most energy to do their favorite things. The researchers found that among the 6th graders--who were 11 to 12 years old--puberty had a significant influence on the change to the pattern of sleeping late and rising late. Psychosocial factors such as academic and social demands had far less to do with that shift than the researchers had expected.
But this pattern was only significant in girls. Carskadon and her team presume that the gender difference stems from a higher percentage of girls in the study group having matured more fully than the boys.
The idea that the shift to a later sleep pattern in adolescence may be brought on by a biological process marks a departure from conventional thinking on the topic. Many in the field have traditionally thought such psychosocial factors as peer influences, the reach for independence, rebelliousness, or more time needed for homework in high school were behind the change.
But if peer-group pressures were causing the shift, those 6th graders in middle schools should have preferred a later phase because of the influence of older peers. And that was not the case.
The results of this study "gave us the first concrete evidence for trying to look at the biological side," says Carskadon, whose research is supported by the National Institute of Mental Health.
Snoozing for Science
To understand the changes that biology may have on the body's internal clock, Carskadon and her colleagues have also been observing students up close in her sleep laboratory here on the campus of Butler Hospital, a Brown-affiliated psychiatric center. To be able to focus on the changes puberty alone brings to children's sleep, the researchers are studying boys and girls who are all about the same age--11, 12, or 13--but who are at different stages of puberty.
By having the students follow first their own sleep schedule and then a prescribed one, both at home and in the lab, the researchers try to get the children's body clocks operating on what Carskadon calls "free run." That way, the scientists can learn what sleep schedule the young bodies would choose without any of the outside influences of family, school, friends, or cues given by daylight.
To know what time the body thinks it is, the researchers take saliva samples during the students' waking hours. An analysis of the saliva reveals the level of a brain hormone called melatonin. Its presence is linked to the regulation of the body's internal sleep clock.
Information about the transitions from night to day and back again travel from the human eye to the hypothalamus area of the brain. The message then goes to a collection of nerve cells in the neck. From there, the message travels to the pineal gland, another brain structure, which makes and releases melatonin.
This past summer, 16 students from local schools volunteered to take part in a study that lasted nearly a month. For their time, they received $150 cash and a $100 savings bond.
As the last group of subjects was waking up in the lab one day last August, the teenagers seemed oblivious to the hour--noon--or the brilliant sunshine outside. The four students, all boys, were propped up in their beds in four single rooms that resembled those in a college dormitory, albeit windowless ones. They were to remain in bed, awake, for the next 34 hours. But they didn't seem to mind. They played games like Connect Four and Monopoly and watched videos with college-student volunteers.
It may have seemed like a weird kind of camp to the students, but the researchers and the electronic monitors were constantly on the watch. Video cameras beamed the boys' images back to the researchers' workstations. The wire leads taped to their faces connected to polygraphs that recorded the activity of their brains, hearts, muscles, and eyes as red-ink peaks and valleys.
While they were awake, the subjects took tests to check their alertness and ability to perform simple tasks. These tests get at when it is their bodies want them to sleep.
It was the fact that the school-transition group had performed poorly on these same kinds of tasks that gave Carskadon and Wolfson insight into the effects of an early school schedule. It became clear that when the biology of phase delay butts up against a school schedule, the kids suffer.
Getting a Later Start
In 1994, after hearing a presentation by Carskadon, members of the Minnesota Medical Association took to heart her work on adolescents, school, and sleep. In a letter to all school superintendents in the state, the mma urged districts to abandon early school starting hours. This year, they followed up with a survey of school districts. But a preliminary look at the results indicates none has changed school start times.
"If, in fact, schools are set up to educate our children, we've got to change things," says Mark W. Mahowald, the director of the Minnesota Regional Sleep Disorders Center at Hennepin County Medical Center in Minneapolis. Such noneducational factors as busing schedules and after-school athletics, he argues, have driven the push to start school earlier and earlier.
"Sending kids to school sleep-deprived does not work to promote learning," Mahowald adds. He says educators need to buck the societal stereotype that people who need more sleep are lazy.
Carskadon knows administrators have a lot on their minds. But based on her work, she would ask them to consider students' sleep needs--in addition to school-bus logistics and after-school activities--when setting a daily schedule. To Carskadon, it would make much more sense to have the older students start later in the morning and have the elementary schoolers, who are early risers anyway, be the ones to meet a 7:30 first bell. In many districts, it's just the opposite.
"I think certainly some school districts are asking more of many teenagers than they're capable of doing," Carskadon says. "Sometimes, I think they get so caught up in all the other factors, if they stepped back and thought about what they're asking of kids, it wouldn't make much sense to them either."
Based on the research Carskadon and her colleagues have done, maybe administrators should take student sleep into consideration, says John A. Lammel, the director of high school services at the National Association of Secondary School Principals. But he cautions: "The reality is that sometimes you have to go when buses are available, you have to go when parents are available." Schools also have to set a schedule that gets in the instructional hours prescribed by the state, he says.
"We don't want to discount optimum learning conditions or optimum learning times," Lammel says. But it's a challenge to find the proper balance.
"There has to be some structure in life," Lammel adds. "You have a time to be on the job, to be in school. Á You need to adjust your personal life a bit to that particular need."
More information on this topic is available from:
Carskadon, M. A. (1990). Patterns of sleep and sleepiness in adolescents. Pediatrician, 17, 5-12.
Carskadon, M. A., Vieira, C., & Acebo, C. (1993). Association between puberty and delayed phase preference. Sleep, 16(3), 258-262.
Carskadon, M. A., Wolfson, A. R., Tzischinsky, O., & Acebo, C. (1995). Early school schedules modify adolescent sleepiness. Sleep Research, 24, 92.
National Sleep Foundation
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Vol. 15, Issue 06